ALBERT

Description: SUMMARYExperiments with winter wheat in 1972 and 1973 tested all combinations of ‘Nitro-Chalk’ ν. liquid N-fertilizer, 56 ν. 112 kg N/ha, 0 ν 5·6 1/ha of herbicide (2·8 kg acid equivalent/ha) and 0 ν 0·7 1/ha of mildew fungicide, all applied at growth stage 4–5 of the Feekes scale. The liquid fertilizer (26 % N) was a solution of ammonium nitrate and urea, the herbicide was a mixture of dichlorprop and MCPA and the mildew fungicide contained 75 % (w/v) of the active ingredient tridemorph.The herbicide and mildew fungicide were sprayed either alone or together and neither scorched the wheat leaves. Liquid N-fertilizer by itself slightly scorched the wheat leaves and scorch was increased by adding herbicide to it, but more by adding the fungicide and most by adding both; it was then severe, especially with 112 kg N/ha.Weed control after adding herbicide to the liquid fertilizer was at least as good as from herbicide sprayed alone.In July, foliar diseases were much more severe with 112 than with 56 kg N/ha, but effects of the other treatments, including fungicide, on foliar diseases, were then very small.With 56 kg N/ha, yields were slightly larger with ‘Nitro-Chalk’ alone than with the liquid N-fertilizer alone, but with 112 kg N/ha they were slightly larger with the liquid fertilizer; adding herbicide to the liquid fertilizer did not change these results. With either amount of N, adding mildew fungicide to the liquid fertilizer made it less good than ‘Nitro-Chalk’, presumably because of the damage from leaf scorch; adding both herbicide and fungicide to the liquid fertilizer increased the damage.

Description: SUMMARYOne hundred and fifty-six Scottish Blackface ewes were differentially group-fed over a 2-month period to achieve three distinct levels of body condition (good, moderate and very poor). Over 5 weeks prior to mating, one group of good-condition ewes was maintained in that condition, one group of good- and one of moderate-condition ewes were brought down in condition by restricted feeding and one group of moderate and the very poor condition ewes were raised in condition by a high level of feeding. Ewes were therefore in good, moderately good or poor condition at mating. After mating, ewes were killed either on return to service or at 25 ± 5 days for counts of corpora lutea and viable embryos.Poor body condition, irrespective of feeding level, was associated with a delay or suppression of oestrus and with a high return-to-service rate. Ovulation rate was positively related to body condition at mating but not to the level of pre-mating food intake at the condition levels studied.Embryo mortality decreased as body condition at mating increased and the interaction between condition and the level of pre-mating food intake had a differential effect on mortality of single- and multiple-shed ova. The lowest rate of embryo mortality was found in ewes in moderately good condition which had been well-fed before mating.

Description: SUMMARYSoil amendments, gypsum, wheat straw mulch and animal manure, were tested on P. vulgaris at toxic and nontoxic sodium chloride levels in the soil. Slower growth rate and gradual death of seedlings were found under saline conditions.Gypsum and straw mulch increased bean tolerance to salinity which was associated with higher plant survival and greater plant vigour.Seed yield/ha was increased by an average of about 30 and 50% with gypsum and straw mulch treatments, respectively, and the gypsum plus straw mulch treatment resulted in an increase of about 100% in seed yield. Number of plants survived and to a lesser degree seed weight were the predominant factors affecting seed yield/ha. The analysis of multiple correlation showed that variation in yield/ha was attributable most to the number of plants/m2.

Description: SUMMARYCowpea and hyacinth bean nodulated and grew well at 11–14 h and poorly at 8 h light duration. Nodulation and plant growth increased with increase in light intensity from 1·4 to 17·1 W/m2 but the natural light intensity (228·3 W/m2) inhibited nodulation in July and plant growth in December.Nodulation and growth of both crops were best at ‘moderate’ temperature and cowpea tolerated ‘warm’ more than ‘cool’ temperatures whereas hyacinth bean showed the reverse situation.Inoculation improved nodulation of cowpea but not hyacinth bean. Application of nitrogen did not improve the growth of plants affected by light and temperature.

Description: SUMMARYResults are presented from four experiments in which comparisons were made between isogenic sterile and fertile plants of maize to study the effects of grain content on yield and quality of shoot dry matter. In two experiments comparisons were made over a range of densities, extending from 5 to 25 plants/m2 in 1972 and 5 to 20 plants/m2 in 1973. The other two experiments, grown in 1974 at a density of 10 plants/m2, were sampled 30, 60 and 90 days after flowering.In 1972 and 1973 yield of shoot dry material was about 10% higher in fertile plants at the lowest density, 5 plants/m2, but grain formation had a negligible effect at higher densities. In 1974, at 10 plants/m2, the yield advantage for fertile plants was 6–7%. These results are in line with other European data, but show a much smaller effect of grain formation on shoot dry matter yield than is normally recorded in USA trials. The discrepancies probably reflect differences in environmental conditions.Absence of grain had little effect on contents of nitrogen, ash and in vitro digestible dry matter, and increased content of pepsin soluble material and hot water soluble carbohydrates. Percentage content of dry matter in the shoot was higher in fertile plants in 1973, and during the later stages of crop development in 1974.The results suggest that the importance attached to high grain content as an essential requirement for yield and quality in forage maize is exaggerated, and that the restriction of maize breeding and testing programmes to assessments of grain production, in the belief that the best grain varieties will also be best for forage, can no longer be justified in northern European countries.

Description: SUMMARYIn 18 digestibility experiments with sheep, 9 diets consisting of single-grass hays and 9 diets each consisting of equal quantities of a good and poor quality hay were fed. Correlations between the voluntary intake of organic matter, digested organic matter, total cell wall and digested cell wall in all possible combinations were investigated. There were no significant differences among the simple correlation coefficients for hays fed singly or as mixtures, even though they were eaten in very different amounts. The simple pooled correlationswere significant (P 〈 0·01) among voluntary intake, digested organic matter and cell wall. The cell wall was significantly correlated with digested cell wall, but there was no simple correlation between voluntary intake and digested cell wall. However, when considered together in a multiple linear model they explained 58% of the variation in voluntary intake compared with 43% explained by the total cell wall alone. The additional variation accounted for by the digested cell wall was significant (P 〈 0·05).The relative importance of the total cell wall and digested cell wall is discussed in relation to selection in grass breeding.

Description: SUMMARYA total of 580 Friesian cows from four dairy farms selected at random were grouped by teat shape. The incidence of teat cup crawl was recorded at the time of afternoon milking.Teat cup crawl was significantly higher (27·4%) in the cows with cylindrical shape teats than in cows with funnel shape teats (8·1%).Milk yield was significantly higher in the cows with funnel shape teats than in cows with cylindrical shape teats. There was significant reduction in milk yield due to teat cup crawl in both groups of cows, the reduction in milk yield being higher in the cows with cylindrical shape teats.

Description: SUMMARYStudies on the adaptation of cattle to the hydrolysis of biuret and on the response of rumen ammonia level to the introduction of 50, 100 or 150 g of feed-grade biuret showed that (1) the rate of ruminal adaptation to the hydrolysis of biuret increased to a maximum effective level of about 350 mg/24 h/100 ml within 10 days when a readily available energy source was fed, (2) a single dose of 50, 100 or 150 g/day of biuret was associated with a prolonged increase of rumen NH3 concentration. The magnitude of the increase was 8–9 mg/100 ml for every 50 g of added biuret, (3) adapted rumens retained their biuretolytic activity for several weeks, and responded to the re-introduction of biuret into the diet by increasing to a near maximum rate within 24–48 h.

Description: SUMMARYSkin samples were used to evaluate the developing skin follicle population of Cheviot × Dorset Horn cross foetuses. The follicle population was studied from the first appearance of skin follicles (55 days' gestation) to the end of gestation. The pattern of development of primary and secondary follicles is described, and compared with the data available for other breeds. The occurrence of secondary follicle branching, previously confirmed only in the Merino, is described, and the ‘prenatal check’, an important feature of follicle development which had not previously been investigated in prenatal studies, is briefly discussed.

Description: SUMMARYTwo methods of analysis of variance of experiments involving diallel arrangements of binary mixtures and monocultures where the former are each represented by a linear replacement series (de Wit, 1960) to detect mean quadratic and quartic patterns among the monocultures and different mixture types, and array differences with respect to linear, quadratic, cubic and quartic effects are given. These are applied to data from an experiment on Italian ryegrass where the four varieties 1145 and S. 22 (diploid), IG2 and Tetila (tetraploid) are mixed in the proportions 75:25, 50:50 and 25:75.Significant mean quadratic effects for D.M. yield at certain harvests are due to higher yields from monocultures than mixtures, and a mean quartic effect at one harvest reflects a lower yield from 75:25 mixtures than 50:50 mixtures or monocultures. Array differences for linear and quadratic effects are largely a property of the ploidy contrast. Specific mixture effects were recognized for two varietal combinations, mixtures between the two tetraploid varieties showing some yield depression, and those between the two commercial varieties (RvP and Tetila) a considerable increase. No meaningful significant effects were detected for in vitro digestibility.Further analysis of total D.M. yield by means of the regression of array covariance (Wr) on to array variance (Vr) show, as expected, a closer relationship of Wr and Vr with the non-recurrent component at a frequency of 75% than at 50% or 25%, but the significant departure of the slope from unity is interpreted as evidence that no reliable information as to the relative competitive abilities of the varieties can be obtained from these statistics. Examination of the de Wit replacement graphs strongly suggests a ranking of competitive ability which accords with the known morphology of the varieties.

Description: SUMMARYEwe reproductive traits of imported Merino local Ossimi and Barki, their first crosses, backcrosses to Merino and the interbred groups of the backcrosses, were considered in this study. Records of 2168 ewes born from 1960 through 1970 were used in the study; they totalled 6959 records.Reproductive performance was different in the three purebred groups, with more multiple births but more lamb losses and abortions in Merinos. However, the three groups weaned similar numbers of lambs/ewe run with the rams (0·98). Merino × Ossimi ewes had the best performance, they lambed and weaned 27% more lambs than local Ossimi. They were followed by MB ewes weaning 0·96 lambs/ewe run with the rams. Reproductive performance of the backcross ewes was lower than that of the first cross, but still better than the purebred groups. Inter-breeding of back-crosses reduced their hybrid vigour markedly.Non-maternal heterosis contributed greatly to the reproductive performance of cross-bred ewes, while the effect of maternal heterosis on reproductive traits was fairly small.Multiple births showed least heterotic effect.

Description: SUMMARYThe development of stable suckling order, the incidence of fighting when suckling, weight gain during the suckling period, and the severity of facial wounding were studied with litters of piglets in which the canine and lateral incisor teeth were either clipped at birth or left intact. Facial wounding was largely confined to litters with unclipped teeth. Severity of wounding correlated with the observed incidence of fighting on the udder (P

Description: SUMMARYThe digestibility and intake by sheep of a neutral mixture of alkali-treated straw and grass silage was compared with an all-silage diet, mixtures of treated straw and silage adjusted to pH of 4 and 10 and with mixtures of untreated straw and silage. Treatment of the straw with alkali increased the digestibility of the organic matter from 46% to 68%. The daily intake of dry matter and digestible organic matter of the neutral, treated-straw/silage mixture was 24·1 and 15·0 compared with 14·7 and 8·8 g/kg live weight for the untreated straw/silage mixture. The sheep when fed ad libitum ate more of the neutral mixture than they did of the mixtures made acid (pH 4·0) and alkaline (pH 10·0) or of the grass silage although the differences were not significant. Calves were fed similar diets of grass silage, a neutral mixture of treated straw and silage and treated straw and grass silage offered without premixing. The calves offered the neutral mixture ate 16·0% more dry matter and 14·5% more organic matter than did the calves offered either silage alone or the unmixed diet and gained live weight at the rate of 0·42 kg/head/day compared with 0·44 for the silage alone and 0·37 for the unmixed diet.

Description: SUMMARYFifty-four British Friesian castrated male calves, initially 3, 6 or 9 months of age (107, 180 and 249 kg initial live weight, respectively), were individually fed for 83 days on maize silage (27·9% dry matter (D.M.), 10·7% crude protein in D.M.), offered ad libitum. Silage was offered either alone or supplemented with cobs of dried lucerne (21% of total D.M. intake). Three levels of urea (0, 1 and 2% of silage D.M.) were added to the silage before feeding.Total D.M. intakes averaged 23·0, 23·4 and 21·6 g/kg live weight (LW) for the 3-, 6- and 9-month-old animals, respectively. Addition of urea increased silage intake by 11% in the 6-month-old group but there was little effect in the 3- and 9-month-old groups. Lucerne supplementation reduced silage D.M. intake from 22·0 to 18·4 g/kg LW (P 〈 0·001) and increased total D.M. intake by 1·4 g/kg LW (P 〈 0·001).Live-weight gain (LWG) of the cattle fed on silage alone increased (P 〈 0·001) with increasing age of animal. The main effect of urea was to elevate (P 〈 0·001) LWG from an average of 0·79 (no urea) to 0·94 kg/head/day (2% urea). However, it appeared that most of this effect was confined to the 6-month-old group. The effect of lucerne on LWG decreased with increasing age of animal (P 〈 0·001). Inclusion of lucerne in the diet significantly reduced the response to urea (P 〈 0·05).Feed conversion efficiency (LWG/100 Mcal DE intake) decreased (P 〈 0·01) with increasing age of animal but increased with urea addition from an average of 4·7 (no urea) to 5·3 kg LWG/100 Meal DE intake (2% urea). The response to lucerne supplementation in terms of efficiency was greatest in the 3-month-old group and thereafter declined markedly with increasing age of animal.The results of this experiment indicated that cattle older than 6 months of age (180 kg LW) could achieve a rate of growth of 1·0 kg/head/day on maize silage supplemented solely with urea, but that younger animals required supplementary lucerne to support a high rate of live-weight gain.

Description: SUMMARYStudies were carried out to measure the productivity of selections for extreme expression of the various components of canopy structure from within six Lolium populations of contrasting morphology.Considerable variation existed for all canopy characters within each base population and this was reflected in the difference between the high and low selections.In the first harvest year productivity was closely positively correlated with leaf length. Although some significant differences in yield occurred between selections for other characters, no general pattern was evident as with leaf length. Within the base populations differences in yield occurred between selections of similar leaf length, emphasizing the role of other physiological factors in controlling yield.In general, dry-matter production was greater in the first harvest year than in the second harvest year. In the second year the long-leaved selections from L. multiflorum and L. multiflorum × L. perenne continued to produce greater yields than their respective short-leaved selections and base populations, but no such differences were evident in L. perenne S. 23 and S. 23 × Ba 6280. Whilst long-leaved selections from the former group were as persistent, or even more persistent than their base populations, the long-leaved selections from L. perenne S. 23 and S. 23 × Ba 6280 showed a lower persistency. Similarly, whilst erect tiller selections from L. multiflorum and L. multiflorum × L. perenne were as or more persistent than their base populations, the three L. perenne erect tiller selections exhibited reduced persistency.The plant breeding implications of these results are discussed.

Description: SUMMARYSeeds of wild safflower, Carthamus oxyacantha Bieb., collected from the Bajgah area, Iran, were subjected to chilling and/or scarification and their germination and emergence characteristics and seedling growth were studied in two laboratory experiments. Seeds of Arak 2811 variety of cultivated safflower, C. tinctorius L., harvested from the same area at the same time was used for comparison.In the first experiment, the untreated, scarified, chilled at 0 °C for 1 month, and chilled and scarified wild seed and seed of the variety Arak 2811 were incubated at six different temperatures (5, 10, 15, 20, 25 and 30 °C) and their germination percentage and seedling lengths were recorded. In the second experiment, the seeds of the above five treatments were planted in a silty clay loam at room temperature (23 ± 2 °C) and their emergence and seedling heights were noted.In all cases, the cultivated variety, Arak 2811, had higher germination and emergence percentages and seedling heights than the wild type. Germination of both strains was greatly reduced at the two extreme temperatures (5 and 30 °C). The optimum temperatures for germination of the wild and the cultivated strains were between 15 and 20 °C.Scarification of the wild seed did not improve the germination or emergence percentages and chilling of the seed for a month at 0 °C reduced the emergence of the wild seed. Temperature of germination, however, seemed to be an important factor affecting germination and seedling growth of wild safflower.

Description: SUMMARYA condition known as ‘scorch” with symptoms similar to copper deficiency often occurs in dry weather on cereals grown on a sandy soil (at Woburn) with an unstable structure. Plants with symptoms contained more sulphur than normal and sulphur/ copper interactions were suspected.Sulphur fertilizers tested in two pot experiments with this soil did not induce copper deficienciesbut increased grain and straw yields of spring wheat especially at higher nitrogen rates. Yields were increased when the mature grain contained less than 0.12% S and the straw less than 0.5% Sin the dry matter. Sulphur concentrations were larger in plants grown in the greenhouse rather than in growth cabinets and in plants grown in oven-dried rather than air-dried soil.Soil-applied copper sulphate slightly increased grain yields in pots but in one experiment there were no corresponding increases in copper contents of the crop. In a field experiment where ‘scorch’ symptoms occurred in 1972, copper oxychloride sprays increased copper concentrations but not yields of the grain.These results suggest that copper deficiency is unlikely to be a primary cause of ‘scorch’ symptoms.

Description: SUMMARYA 2 × 3 factorial trial designed to investigate the effects of castration and three diets on growth and body composition of 30 male Dorset Horn × (Border Leicester × Merino) lambs is described. The three diets were: (a) a standard ration of equal weights of lucerne chaff and pelleted concentrates; (b) a similar ration to (a) plus 7·5% by weight of lipid (peanut oil and tallow); (c) a greater ration of (a) calculated to be isocaloric for digestible energy with diet (b).At the beginning of the trial a group of 40 lambs (20 rams, 20 wethers) were shorn and five rams and five wethers were selected at random and slaughtered to establish initial body composition. The remaining 30 lambs, 15 rams and 15 wethers aged about 22 weeks and having mean weights of 33·0 kg (rams) and 31·2 kg (wethers), were randomly divided within sex into three groups and allocated to the three diets for 92 days. At the end of this period the lambs were again shorn, and then slaughtered and dressed.During the trial, rams gained significantly (P 〈 0·001) more weight than wethers, and lambs on diet (a) gained significantly (P 〈 0·01) less weight than those on (b) and (c). Weight gains on the latter two diets were similar. Diet generally had little effect on body composition, although there was a tendency, within sexes, for lambs on diet (b) to have a greater fat content than those on the other diets. Rams had significantly greater carcass weights (P 〈 0·01), head percentage (P 〈 0·001) and various m. longissimus dorsi dimensions than wethers, but significantly less fat in all the locations measured, including a lower percentage of chemically extractible fat in the offals and carcasses. Estimations of the energy stored in the wool-free body during the trial indicated that wethers stored significantly more energy in the form of fat than rams (P 〈 0·001), but that rams stored significantly more non-fat energy than wethers (P 〈 0·001). It is concluded that a maximum growth rate exists for the non-fat body, and that it is higher in rams than wethers. Thus the addition of dietary lipid (which increases energy intake with comparatively small increases in weight or volume of feed), is more likely to promote fat deposition in wethers, which have a lower maximum capacity for non-fat storage, than in rams.

Description: SUMMARYThe actual transpiration of Mexipak wheat (Triticum aestivium L.) was determined by the inflow-outflow method and by soil moisture determination by the use of a neutron probe and gravimetrically. Three irrigation treatments were used during the 1969 season, wet, medium and dry. Amounts of water given were 370, 310 and 255 mm for wet, medium and dry treatments respectively. One irrigation treatment was used during the 1971 and 1972 seasons in which 620 and 700 mm of water respectively was given. However, during the 1973 season, two wet irrigation treatments of 560 and 670 mm of water were used. Values of Et measured by different methods were closely related. Seasonal averages of Et were 2·55, 1·99 and 1·62 mm/day for wet, medium and dry treatments respectively. The empirical coefficient (f = Et/Eo) under wet treatment, was found to be higher than that given by Penman (1956) for short grasses and higher than that obtained by Boumans et al. (1963) for wheat and barley in Iraq. The empirical coefficient Kb in the Blaney-Criddle formula was less than the value given by Blaney & Criddle (1950) for an arid climate and less than the value obtained by Boumans et al. (1963) for wheat in Iraq. The water use efficiency for grain production was greater under dry than under wet treatment.

Description: SUMMARYIn view of the dependence of fat metabolism on the size of fat cells and the lack of information describing the change in fat cell size which occurs during growth in pigs, an examination was made of the size of subcutaneous fat cells in Pietrain and Large White pigs of 30–95 kg live weight. A microscopic procedure was used and fat cell diameter was measured at two levels in the outer layer of shoulder fat and at two levels in the inner layer.In both breeds the rate at which cell diameter increased in size with live weight was greater in the inner layer than the outer layer. At all levels this rate of increase was greater in Pietrains. At the two levels in the inner layer the cells from Pietrains increased in size by 41% and 54% between 30 and 95 kg live weight and the cells from Large Whites increased in size by 23% and 36%. The result was that at 95 kg live weight both breeds had cells of similar size in the inner layer.Therefore in pigs of the same live weight, cell size varies, depending on the site at which the examination is made and the breed of pig. Even at constant cell size, however, the lipogenic capacity of the fat from different levels and different breeds must be different since the cells increase in size at different rates.

Description: SUMMARYOne pot and five field experiments were made to study different aspects of the competition between R. exaltata and maize.The growth of young maize plants was not inhibited by being grown together in pots with young R. exaltata plants. In the field the soil tended to be somewhat wetter when the two species were grown together than when maize was grown alone, and was wettest with R. exaltata grown alone. Maize grain and total yield decreased and shoot yield of R. exaltata increased with R. exaltata plant density on both irrigated and unirrigated blocks of land, but yields were not much affected on either block by increase in plant density of maize or in nitrogen supply; maize yield was increased by irrigation but that of R. exaltata was not. Maize plant arrangement did not greatly affect maize grain and total yield or R. exaltata shoot yield, nor did arrangement of R. exaltata plants have much influence on their depression of maize yield, but R. exaltata caused a greater decrease in the grain yield of a short than of a tall maize cultivar.R. exaltata plants germinating at the same time as the crop plants did not have much effect on maize grain yield if they were removed by 8 weeks after the seedlings emerged, but decreased it considerably if allowed to remain for 12 weeks or more; weeds sown 2 or more weeks after the maize emerged hardly grew and had little effect on maize yield. When maize and R. exaltata were grown together leaf area of the maize was little affected up to the time of flowering, but was decreased after flowering, while leaf area of the weed was greatly depressed. Up to 7–8 weeks after seedling emergence more of the ground area was covered by foliage when maize was grown with R. exaltata than when it was grown alone, but later the ground was completely covered by foliage in both cases. Dry weight of grain and shoot of maize increased and that of shoot of R. exaltata decreased when the weed plants were shortened with growth regulators.

Description: SUMMARYThe studies were designed for breeding resistant varieties of rice to bacterial leaf blightcaused by Xanlhomonas oryzae (Uyeda et Ishiyama) Dowson with induced mutations. In 1971, seedlings of irradiated lines (X$) originated from treatments of 60Co γ-and X-radiation and control (C6), which were propagated in bulk up to X6(C6) generations after the treatments, were inoculated with highly virulent isolates.The results showed that the variability of disease reaction within the irradiated lines increased in both resistant and susceptible directions from the control mean. It was assumed from these results that the irradiation treatments could induce polygenic mutations to give both germ types more resistant and those more susceptible to bacterial leaf blight, suggesting that such treatments might be an effective approach for breeding varieties resistant to the disease.

Description: SUMMARYOf a group of 24 pregnant Scottish Blackface sheep 12 were killed at the outset and the remainder offered, ad libitum, a poor quality hay. At the end of pregnancy seven more were killed and the remainder offered, during lactation, 3 kg/head/day of a semipurified diet of 64% dry-matter (D.M.) digestibility, and containing 18% crude protein (CP), 1·17% Ca and 0·82% P in the D.M. Milk production was determined at weekly intervals and milk samples obtained at these times for estimation of Ca and P concentrations. These sheep were killed 42 days post-partum. The shorn empty bodies were analysed for fat, protein, Ca and P contents.The feeding of the poor quality hay caused losses of 76, 37, 15 and 15% of the body contents of fat, protein, Ca and P, respectively, during pregnancy. Despite maintaining a moderate milk yield (1·5 kg/day) the ewes were in positive Ca and P balance during early lactation and had restored the skeleton to its initial mineral content by 42 days post-partum. The rate of absorption of Ca was calculated to have been at least 115 mg/ kg body weight (BW) which is double other estimates in the literature for sheep at this stage of lactation.These differences are discussed in relation to mechanisms for adaptation of Ca metabolism which have been proposed for other species.

Description: SUMMARYFifty-nine full-sib progenies produced in a North Carolina Model I design were assessed fortotal yield (sum of three harvests) under four treatments differing in plot size and density. The treatments were: swards of 0.25 m2, spaced plants at 0.6 x 0.6 m and single and double rowswith 0.3 m betweenrows and 0.15 m between plants, with ten plants per row. Estimates of plot heritabilities ranged from 0.24 for spaced plants to 0.59 for double rows. Heritability in the sward was 0.35. Additive genetic correlations between the sward and the other treatments were surprisingly high: about + 0.86 for the spaced plants and between +0.8 and +0.9 for the row plots. The implications of these estimates for the relative selection efficiencies of the non-sward treatments are discussed.

Description: SUMMARYOestrus, ovulation rate and prenatal mortality were studied in 114 mature Merino ewes of high and low body weight at mating. Three nutritional treatments were imposed over 8 weeks prior to hand mating to fertile rams; high plane (HH), low plane (LL) and 7 weeks of high plane followed by 1 week of fasting immediately prior to mating (HL). Ovarian activity, ovulation rate and the extent and timing of prenatal loss were assessed by the appropriate use of direct ovarian observations, pregnancy diagnosis, returns to service and lambing records.While both prolonged undernutrition (LL) and acute nutritional restriction (HL) were associated with some suppression of behavioural oestrus, neither had any appreciable effect on ovulation rate or prenatal mortality. In all groups the right ovary was more active in producing ova than the left, and the HH group had more ovarian follicles (≥ 4 mm diameter) than the other two groups. Large unruptured ovarian follicles (6—15 mm diameter) were observed in nine ewes. Significantly more ova shed in multiple ovulations were lost, and multiple-ovulating ewes were more likely to suffer complete rather than partial loss of both embryos. Impaired fertility was evident when ewes that returned to service at an extended cycle length were re-mated.

Description: SUMMARYResidual effects of N, P and K applied to cotton on the following crops of dura (Sorghum vulgare), lubia (Dolichos lablab) and wheat (Triticum vulgare) were investigated using data obtained over a 30-year period from a factorial field experiment including various levels of the three nutrients. The three crops differed in their response to residual N, P and K. Dura and wheat, being nitrogen depleters highly responsive to fertilizer nitrogen, were consistently affected by residual N. The residual effects of N on grain and straw yields of both dura and wheat were significant in all seasons and the effects were proportional to the amount of N applied to the preceding cotton. There were indications, however, that a much greater part of the N applied in the preceding year was not available to the succeeding crop. Residual P did not have a significant effect on dura but it varied in its effect on the different components of wheat in different seasons. Residual K did not have any effect on dura or wheat. Data on nutrient uptake and composition of wheat tended to support the yield responses. Contrary to the response of the two cereal crops lubia, being a nitrogen fixing legume, did not respond to the effect of residual N and was consistently affected by residual P. Residual K had a slight effect on lubia in only a few seasons.

Description: SUMMARYSeven hundred and twenty-five adult ewes of six breeds, namely Marwari, Chokla, Magra, Pugal, Jaisalmeri and Russian Merino x Marwari (F1) were typed for blood potassium, haemoglobin and erythrocyte-reduced glutathione (GSH) types. The nature of the association between each polymorphic trait and wool production efficiency (wool yield per kg body weight) in these breeds has been examined.GSHh animals were predominant in all the breeds. A negative correlation was observed between wool production per kg body weight and erythrocyte glutathione level. In general, mean wool production per kg body weight was found to be more in animals of Hb type A than in other Hb type animals. No significant correlation between blood potassium level and wool production per kg body weight was found in any of these breeds.

Description: SummaryA radiography unit was developed with which two technicians and two assistants were able to diagnose number of foetuses in 400–600 ewes per day on farms. Diagnoses made between 100 and 120 days of gestation in flocks where weekly mating records were made were 95–98% accurate as judged by lambing records. In most flocks more than 90% of twin pregnancies were correctly diagnosed. Agreement between diagnoses and lambing records was reduced when weekly mating records were not available. The radiographic examination had no detrimental effects on ewes or lambs.

Description: SummaryA winter barley variety, from the USSR, 13031, lacking vernalization requirement but sensitive to short days and more frost resistant than varieties now commercially grown in Britain, was hybridized with Shimabara, a Japanese variety which requires vernalization but is less sensitive to short days and more susceptible to frost than 13031. The resulting segregating population was then selected under short days and non-vernalizing conditions and in artificial freezing tests, in order to isolate recombinant lines.Five lines derived in this way, together with the parents and the standard winter barley variety, Maris Otter, were included in a detailed developmental study made in a glasshouse under cool, short days.Four of the lines had very similar developmental characters, namely few leaves and a high rate but short duration of spikelet initiation. Developmentally these selections resembled the parent Shimabara more closely than 13031 but the rate of spikelet initiation was faster than that of either parent and the duration of spikelet initiation was shorter. The fifth selection also resembled Shimabara more closely than 13031 but had more leaves and a lower rate and longer duration of spikelet initiation than the other selections. This selection was found to have a strong vernalization requirement.One selection closely resembled 13031 in its frost resistance but had low short-day sensitivity and no detectable vernalization requirement. The complementary characters of the two parents were therefore recombined in this line.Vernalization had little effect on the development of any of the genotypes under cool, short days in a glasshouse.

Description: SummaryAn experiment was designed to investigate the effect of a sustained lactation pattern on the intake of milk or solid food by lambs and on their consequent growth rate. Normal lactation pattern was compared with sustained lactation, achieved by fostering lambs at 24 days of age on to newly-lambed nurse ewes. Two genotypes of lamb were used; these were pure-bred Scottish Blackface and Textel × Blackface. Lambs were offered one of two qualities of pelleted concentrate food from 4 weeks of age.Maximum daily intakes of milk were 2·16 and 1·87 kg/day, respectively, for fostered and non-fostered lambs. This differential was maintained until the 10th week. Pattern of lactation had no significant effect on total energy intake from milk and solid food combined or on live-weight gain up to 10 weeks of age. Texel cross lambs consumed more food than did pure Blackface lambs and showed correspondingly higher rates of live-weight gain. Lambs ate slightly more of the higher quality pellets than the lower but there was no effect of solid food quality on milk intake. Within breed of lamb there was a negative relationship between intake of milk and of solid food.

Description: SummaryThe rate of production of bacteria in the rumen of buffalo calves kept on two rations was measured using 14C labelled Streptococcus bovis and 35S whole ruminal bacterial cells. The animals received daily either 15–20 kg green maize or 25–30 kg green cow pea in 12 equal amounts at 2-h intervals. The bacterial cells from the rumen of animals maintained on the same diet were tagged with 35S by in vitro incubation in the presence of 35S-sodium sulphate. Similarly Streptococcus bovis of rumen origin was grown in the presence of U-14C dl-leucine. The cells were injected into the rumen in a single dose. The dilution of the specific radioactivity of bacterial cells in the rumen with time was taken for calculation of the turnover time and rate of production of bacteria.The average production rates of bacteria were 88·3 ± 3·88 and 92·3 ± 1·82 g/kg digestible organic matter and 101·8 ± 1·55 and 103·3 ± 1·49 g/kg digestible organic matter in animals fed green maize and cow pea, when estimated by using mixed rumen whole bacterial cells and Streptococcus bovis respectively. There was no significant difference in the rate of bacteria production when estimated by either method.

Description: SummaryA technique is described which uses the ratio of the natural 12C and 13C isotopes of carbon to calculate the proportions of Calvin pathway (or C3) species and C4 dicarboxylic acid pathway (or C4) species in mixed samples of shoots, roots or seeds. Mean percentage of a particular component can be predicted to within ± 2% of actual values with average standard errors of less than 1% with two component mixtures under good conditions using threefold replication. The technique is particularly useful for estimating the proportion of C3 and C4 species in samples of visually indistinguishable, intermingled root systems from mixed field communities or from competition experiments. The proportion of C3 and C4 species in both oesophageal fistula and feed samples can be obtained using this technique, and it is proposed that data from fistula and pasture samples could be used to determine the extent to which animals selectively eat C3 or C4 species. The advantages and disadvantages of the technique are discussed.

Description: SummaryA comparison was made between an intensive system of lamb production based on Italian ryegrass RvP and one based on perennial ryegrass S. 24, over 2 years, each at three stocking rates (14, 17, 20 ewes/ha). More grass was grown in the first year than in the second when the yield of RvP was particularly reduced. The ewes and lambs ate more RvP than S. 24 but there was no difference in lamb growth rate. The lambs grew faster at the low stocking rate from 0 to 18 weeks and from 0 to slaughter than at the medium and high stocking rates, in both years. Ewe intake and lamb growth rate were higher in the second year than the first. The Masham ewes with two lambs ate significantly more grass per unit of body weight than the Finnish Landrace × Scottish Halfbred and Finnish Landrace × Scottish Blackface ewes, and their lambs grew significantly faster. It was concluded that for an intensive system of lamb production from grass, S. 24 was more suitable than RvP.

Description: SummaryDespite much experimental evidence showing that sodium fertilizer increases sugar–beet yield and decreases need for potassium, there is resistance to its use on some soil types through fears of deterioration in soil structure. Twelve field experiments with sugar beet were made in Eastern England, testing all combinations of autumn and spring applications of 0, 150 and 300 kg Na/ha and 0, 83 and 333 kg K/ha. Fields were chosen with soils of loamy very fine sand, very fine sandy loam, sandy clay loam and clay loam textures. Micro–plot and controlled environment studies were also made with the same soils to examine effects of sodium on seedling emergence and growth.Visual assessments of soil physical state following sodium application revealed no effect in the year sugar beet was grown nor in the following spring when cereals were grown. Measurements of physical properties of soils treated with sodium suggested that applications of several times the recommended amounts of sodium fertilizer would not damage soil structure. However, sodium fertilizer increased the osmotic suction of soil solution which, under some circumstances, e.g. dry springs or giving the fertilizer close to the time of sowing, decreased germination and seedling growth. For this reason and not because it has a detrimental effect on soil physical condition, sodium fertilizer best given in the autumn or some weeks before sowing.

Description: SummaryThe possibility of a sub-clinical state of thiamine deficiency in young cattle and sheep is discussed. A trial was carried out on six MAFF experimental husbandry farms in which groups of animals were given 100 mg of thiamine per day orally throughout the rearing period. Measurement of erythrocyte transketolase showed that the dosed group gave a significantly lower percentage thiamine pyrophosphate effect than the control group. There was no difference in weight gain of the two groups during the limited period of the trial.

Description: SummaryThree spring barley varieties, Proctor, Vada and Mosanne, were inoculated with Rhynchosporium secalis(Oudem.) J. J. Davies at Growth Stages 3, 7, 10·1 and 10·5 (Large, 1954). The treatments included single inoculation at each growth stage and multiple inoculations at two, three and four of the above growth stages. There was no effect of inoculation oil the number of fertile tillers. Thousand-grain weight was reduced in all seven inoculation treatments in Mosanne but only the quadruple inoculation adversely affected the other two varieties. Numbers of grains of both Mosanne and Vada were reduced by treatments which included an inoculation at ear emergence but Proctor was affected only by the quadruple inoculation. In terms of disease assessment Mosanne was very susceptible and Proctor moderately resistant but Vada, with symptom scores only slightly better than Mosanne, exhibited a degree of tolerance which was reflected by the grain weight results in which small increases were recorded. This tolerance mechanism, possibly acting through compensation in this variety, is compared with compensation reported in wheat.

Description: SummarySeventy-four field experiments on the nitrogen requirement of sugar beet were made in eastern England in. 1966 to 1974. Considerable differences in sugar yield response to nitrogen were found between the six soil types used, and these differences were found (on five of the six soils) to be related to sugar yield. Nitrogen response was large on chalk and limestone soils in Lincolnshire, intermediate on East Anglian boulder clays and least on East Anglian chalk and light drift soils. On the lighter soils (limestones, East Anglian chalks and light drifts) nitrogen response was greater with high summer rainfall than with low. Fenland silt soils were very high yielding, but nitrogen response was moderate.Optimum nitrogen rates differed between soils, in the range 100 kg/ha on East Anglian chalks and light drifts to 180–200 kg/ha on Lincolnshire chalks and limestones.

Description: SummaryThe oestrogenic isoflavones genistein, biochanin-A and formononetin, as well as the coumestan derivative coumestrol, were identified by thin-layer, paper and gas chromatography in berseem clover (Trifolium alexandrinum) grown in Israel. Under the conditions studied, the concentration of these oestrogens in the berseem clover (total 〈 0·01% in the dry matter) was considerably lower than those found in clover species known to be associated with infertility in ruminants.

Description: SUMMARYThe effects of six amounts (0, 17, 34, 51, 68 and 85 kg N/ha) of fertilizer N, applied at sowing time as calcium ammonium nitrate, on the crude protein (N × 6·25) content of barley straw sown as the first, second and fourth or later tillage crop after grazed pasture were studied over three seasons at a total of 126 sites. In addition total N uptake and apparent recovery of fertilizer N were calculated for each cropping sequence.The mean crude protein content of the 126 sites was 4·1% without N, increasing to 4·8% with 85 kg N/ha. Maximum protein content with 85 kg N/ha ranged from 4·4% in 1971 to 5·4% in 1973. It was highest in the year which gave the lowest straw yields. Protein content was higher when the barley was sown as the first or second crop after pasture than when it was sown as the fourth or later crop. Incremental of fertilizer N gave only small increases or decreases in straw protein contents. Over all sites straw protein content amounted to about 36% of grain protein contents. There was a significant positive relationship between grain and straw protein contents.Nitrogen uptake in the straw without fertilizer N was 19, 18 and 12 kg/ha in barley sown as the first, second and fourth or later tillage crop after grass. The total uptake of N in the grain and straw combined was 93, 102, 107, 109, 111 and 116 kg N from applications of 0, 17, 34, 51, 68 and 85 kg/ha of fertilizer N. The mean apparent recovery of fertilizer N in the straw varied from 12% with 17 kgN/ha to 8% with 85 kg N/ha.

Description: SummarySix late pregnant and six non-pregnant Finnish Landrace × Dorset Horn ewes were fed a standard diet. Blood and liver samples were taken and the concentrations of the following metabolites measured: adenine monophosphate (AMP), adenine diphosphate (ADP), adenine triphosphate (ATP), citrate, 2-oxoglutarate, phosphoenol-pyruvate, pyruvate, lactate, 2·phosphoglycerate, 3·phosphoglycerate, malate, β·hydroxybutyrate, acetoacetate, glutamate, alanine, NAD+ and NADH. Comparing non-pregnant with pregnant ewes the liver of the pregnant animals had reduced concentrations of lactate, ADP, NAD+ and NADH, and in the blood there were reductions in lactate, pyruvate, lactate/pyruvate ratio and urea. The concentrations of the other metabolites of the pregnant ewes receiving adequate nutrition were little changed from those of the non-pregnant ewes. The significance of these findings is discussed.

Description: SummaryThe effects of paraquat (l, 1'-dimethyl-4, 4'-dipyridylium dichloride or Gramoxone) and diquat (l,1'-ethylene-2, 2'-dipyridylium dichloride or Reglone) on inhibition of flowering and the effect of such an inhibition on improvement of cane yield and juice quality in late maturing sugarcane varieties Co. 853 (early-season flowering) and Co. 419 (mid-late season flowering) planted in February were studied under field conditions at Coimbatore (latitude 11° N). In Co. 419, the spray of paraquat @ 0·35 kg a.i./ha and diquat @ 0·45 kg a.i./ha (diluted in 3000 1 of water) in two equal doses at 3–4 day intervals during the 1st and 2nd week of August suppressed the flowering almost completely, while in Co. 853 flowering could not be checked successfully by chemical spray. Flowering in Co. 853 could be checked only when the spindle leaves were cut continuously from 15 July to 12 August at 4–5 day intervals. In Co. 419, cutting leaf spindles at any day between 1 August and 12 August prevented flowering totally.The sprayed non-flowered crop of Co. 419 gave 13·84–15·69 t/ha more cane yield in February and 16·14–18·07 t/ha in April, whereas sugar yield increased by 1·16 t/ha in February and 3·56 t/ha in April compared with the control flowered crop. There was practically no difference in paraquat and diquat sprays. Suppression of flowering by defoliation in Co. 853 also increased the cane and sugar yield in and after February.

Description: SUMMARYField experiments were conducted at the International Institute of Tropical Agriculture (IITA), Ibadan, Nigeria, for four seasons to evaluate the effect of harvest interval on yield, quality and viability of indeterminate cowpea (Vigna unguiculata (L.) Walp.) seeds. Decreasing harvest frequency from every week to every 4 weeks reduced seed yield, quality and viability. Rate of yield losses was highest at close spacing and intermediate at wide spacing during the first rainy season, and lowest at wide spacing with supplementary irrigation during second rainy season. Time of harvest study conducted with six cultivars indicated that these yield losses were attributable to reduced seed weight and increased pod losses after mature pods were exposed to weathering for more than 1 week. The reduction in seed quality and viability was associated with a high degree of fungal and bacterial infection in the seed. Varietal differences in resistance to weathering were noted among the cultivars tested. TVu 2616 P-O1D, that has thick, leathery pods and smooth, tan seed coat was the most resistant to weathering.

Description: SummaryDuring four winter seasons eight spacing and density experiments were made under irrigated high fertility conditions in north-west Mexico (latitude 27° N). Experiments included various Triticum aestivum and T. durum genotypes of spring habit, short stature derived from Norin 10 genes, and contrasting plant type. Measurements included dry-matter production, photosynthetic area index, and light interception during one experiment, total dry matter at maturity in most others and grain yield and its numerical components in all experiments.Grain yield and most other crop characters were unaffected by row spacings within the range 10–45 cm interrow width. The optimal seeding density for maximum grain yield was 40–100 kg/ha (80–200 plants/m2). Yield reductions at lower densities (20, 25 kg/ha) were slight and accompanied by reduced total dry-matter production. Yield reductions at higher densities (160–300 kg/ha) were also slight and were associated with more spikes/m2 but fewer grains/m2 and reduced harvest index. It is suggested that lower than normal preanthesis solar radiation or weather conditions leading to lodging can magnify these yield depressions at higher densities.Measurements showed rapid approach of crops to 95% light interception, reached even at a density of 50 kg/ha within 50 days of seeding. It is suggested that provided this occurs before the beginning of substantial dry-matter accumulation in the growing spikes (60 days after seeding) there will be no loss of grain yield with reduced seeding density. Results point to a ceiling photosynthetic area index for maximum crop growth rate although there was a tendency for rates to fall at very high indices (〉 9). This tendency was associated with very high density, high maximum numbers of shoots, poor survival of shoots to give spikes (〈 30%) and reduced number of grains/m3;. The relatively low optimal densities seen here may be characteristic of genotypes derived from Norin 10.Genotype × spacing, genotype × density and spacing × density interactions were generally non-significant and always small. There was a tendency for the presence of non-erect leaves or branched spikes to reduce the optimal density, but large differences in tillering capacity had no influence. Differences in lodging susceptibility can however lead to substantial genotype x density interactions.

Description: Output from grazing animals in Britain could be increased by extending the growing season of grasslands. In particular the growth of hill pasture species is highly seasonal with 75% of annual production occurring in three summer months (Newbould, 1974). Stocking rates, limited by winter carrying capacity, are therefore low and summer leaf production is undergrazed. The consequent accumulation of mature senescing herbage seriously reduces pasture quality (Eadie, 1968). As a result of this and lack of grass growth, ewes are often poorly nourished prior to mating (November) and throughout pregnancy and early lactation. Hence fertility levels and lamb birth weights and growth rates are low, and mortality rates high (Gunn, 1967).

Description: SummaryA mathematical model of whole plant growth in soil is presented. Particular emphasis is given to those factors which relate to the absorption of nutrients and water by the root system. There are two basic premises; that a plant is made up of two pools, structural material and precursors to structural material, and that structural material is produced by a reaction between a given ratio of precursors. The precursors are soluble carbohydrate and unbound nitrogen, probably nitrate. Increase in leaf area and root length is a consequence of absorbed nitrogen combining with photosynthate.The absorbing power and the distribution throughout the soil of the roots is controlled, through feedback mechanisms, by the ratio of the precursors, within the plant. The description of plant growth is interfaced with a model of one-dimensional flow of water and solutes in soil, and gives a model for investigating plant growth, or competition between root systems of more than one plant. The results of a number of simulations are presented. A sensitivity coefficient is defined to compare the effect of various properties on overall growth. Its value is calculated for 11 plant properties. It is some measure of the competitive advantage conferred on the plant by a change in the value of each property. The results of the competition experiments are given as replacement diagrams.The model has weaknesses. Because it is explicit, it defines in precise detail the experiments which would support the hypotheses, or suggest modifications to them. As a holistic analysis, it brings together ideas from different disciplines into one comprehensible framework.

Description: SummaryFinnish Landrace sheep with low red cell GSH concentrations resulting from a defective transport system for certain arnino acids were crossed with Tasmanian Merino sheep with a red cell GSH deficiency due to impaired activity of the enzyme γ-glutamyl cysteine synthetase. Inheritance data showed that the two types of GSH deficiency were under independent genetic control. In the Finnish Landrace breed, the gene coding for the transport defect (Trn) was inherited as an autosomal recessive and sheep homozygous for this gene had high red cell concentrations of lysine and ornithine (Ly ×) as well as low levels of GSH. In the Tasmanian Merino breed the GSH deficiency behaved as if controlled by an autosomal dominant gene (GSHL). Backcross breeding experiments resulted in lambs which had inherited both types of GSH deficiency. Evidence suggested that such ‘double low’ GSH lambs had an impaired viability. In Tasmanian Merinos the GSH deficiency was established prior to birth. Newborn Finnish Landrace lambs were clearly separable into two types on the basis of their red cell lysine and ornithine content but not on their GSH concentrations.

Description: Herbage yield obtained from grass swards is influenced by the presence of grazing animals (Brockman, Rope & Stevens, 1971a, b; Holmes, 1968; Shaw, Brockman & Wolton, 1966). The net effect of grazing in a particular situation depends on the balance between the effects of excretal-N return, which tends to increase yields (Brockman & Wolton, 1963) and those of treading and other sward damage, which tend to reduce yields (Edmond, 1970). This net grazing effect on yield can be measured by comparing yields of cut and grazed swards under management that is in all other respects identical (Shaw et al. 1966). Available data have been examined to obtain quantitative estimates of the net effect of grazing and of the changes in these effects that occur with changes in sward N supply.

Description: SummarySplit-plot (or split-block) analyses are commonly applied to experimental results where several successive observations of the same variable have been recorded on each experimental unit. The assumptions required for such analyses receive scant attention and it often seems unlikely that these assumptions would be satisfied in experimental situations. Five sets of results are presented to support this proposition. An alternative analytical approach is suggested in which contrasts over time are analysed; such a method is always valid, computationally simple, and readily interpretable, and may also be used to gauge the validity of the split-plot analysis.

Description: SummaryPrimed continuous intravenous infusions of tracer amounts of [2·3H]gluscose were used to measure glucose entry rates before and after the administration of triamcinolone acetonide or trienbolone acetate to sheep eating 1200 g/day of chopped hay.The intramuscular injection of triamcinolone acetonide caused hyperglycaemia with a maximum plasma glucose concentration 24 h after the injection. Twenty-four hours after the injection of 0·5 mg/kg of steroid the mean glucose entry rate rose from 1·44 to 2·14 mg/min/kg. The difference between these means is significant (P 〈 0·02). Twenty-four hours after injecting 0·05 mg/kg of steroid the mean glucose entry rate had risen from 1·34 to 1·86 mg/min/kg. The difference between these means is significant (P 〈 0·05). The intramuscular injection of trienbolone acetate (0·5 mg/kg) had no effect on plasma glucose concentration or on glucose entry rate.These results are compared with the effect of betamethasone and are discussed in relation to the treatment of ketosis in cattle and sheep.

Description: SummaryLeaf samples were collected, at weekly intervals, throughout the growing season, from potato (Solanum tuberosum L.) plants supplied with varying amounts of nitrogen (0, 60, 120, 180 and 240 kg N/ha) and analysed for total N. Application of nitrogen increased the N concentration in the green leaves at all stages of growth. There was a significant curvilinear relationship between the final tuber yield and the total N concentration in the leaves at 48–90 days after planting in 1968–9 and at 79–107 days after planting in 1969–70. The N concentration at 70–90 days after planting was consistently related to the final tuber yield in both years. Thus this period was ideal for assessing the nitrogen status of potato plants. The critical concentration of total nitrogen generally decreased with advance in age. It ranged from 4·65% at 76 days to 3·30% at 90 days during 1968–9, whereas in 1969–70 it ranged from 4·20% at 79 days to 3·80% at 93 days. During the period from 83 to 86 days the critical percentage was around 3·6% in both the years.

Description: SummaryExamples of response surfaces for pairs of nutrients and results of 41 multi-level experiments with N only were used to compare the goodness-of-fit of polynomial, inverse polynomial, exponential and intersecting-straight-lines models.Whereas no one model fitted best at every site, many results were well represented by two intersecting straight lines and on average, this model had the least residual mean square. Of 17 experiments with spring barley in south western England the few results best represented by smooth curves were from crops much affected by leaf diseases.Fertilizer response was poorly represented by models without a falling asymptote, like the simple exponential and inverse linear. Study of residuals after fitting the quadratic showed that this widely used model consistently over-estimated both the amount of fertilizer needed for maximum yield and the yield loss when too much fertilizer was given.When fitted to the mean yields of each nitrogen treatment, most models had residual mean squares equal to or less than the error mean square, repeating a result obtained at Rothamsted as early as 1927. We question the validity of some well-known evidence for block and treatment additivity.For 12 experiments in 1970, between-site differences in the parameter values of the two straight lines representing grain yield were related to leaf area at ear emergence.

Description: SummaryTwo experiments designed to compare lambs born to Merino ewes subjected to either nutritional deprivation or high ambient temperatures (diurnal: 8 h at 42·2 °C, 16 h at 32·2 °C) during the last two thirds of gestation are described.In Expt 1, lambs from ewes group-fed to maintain maternal body weight at high ambient temperature were lighter (P 〈 0·01) and had shorter metacarpal bones (P 〈 0·01) than those from ewes fed to either lose, maintain or gain weight at prevailing temperatures (– 2·0 °C to + 16·4 °C). The regression of metacarpal length on the cube-root of birth weight (‘linear equivalence’) was linear. Simple maternal under-nutrition was thus not indicated as a cause of foetal stunting in heat-stressed ewes, though the proportions of affected lambs closely resembled those of the nutritional dwarfs.In Expt 2, in which all ewes were individually fed, heat-stressed ewes fed ad libitum consumed 40% less feed and produced lambs which were markedly lighter than those from controls at prevailing temperatures. Other control ewes pair-fed at the level of intake of heat-stressed ewes gave birth to lambs of similar weight to those fed ad libitum. Thus, although feed intake was substantially reduced at high temperatures, the amounts actually eaten by heat-stressed ewes were sufficient to enable control ewes to produce lambs of normal weight. The relationships between birth weight and the weight of the adrenals, cerebellum, cerebrum, heart, kidneys, liver, spleen and thyroid were linear, irrespective of treatment, and as in Expt 1 metacarpal length was linearly related to the linear equivalence of birth weight. However, not all changes in body components were directly proportional to changes in the body as a whole, and heat-affected lambs were thus neither true miniatures nor achondroplastic dwarfs. Until these relationships are clarified it is suggested that ‘stunting’ is the most appropriate description of the influence of high ambient temperature on the sheep foetus.The findings are consistent with the suggestion that the adverse effects of high temperature arise from an extreme form of foetal undernutrition.

Description: SummaryWeed control in irrigated peanuts was evaluated under arid conditions over an 8-year period. Weed competition during the first 8 weeks of the growing season, affected the yield in three out of eight experiments. Mechanical cultivation and herbicides alone or in combination did not control the weed population completely. The best weed control was accomplished by the combination of two herbicides, a system which allowed a complementary effect and long-term control of annual weeds.

Description: SummaryA linear relationship between the amount of allantoin excreted in the urine of cattle and the digestible dry-matter intake, has been found for cattle fed different roughage diets. The relation was also linear for buffalo although they excreted less urinary allantoin than cattle at the same level of digestible dry matter intake. It is postulated that the relationship arises because of the contribution that degraded microbial nucleic acids make to the excreted allantoin in the urine of cattle.

Description: SummaryA number of studies on sodium hydroxide treatment of rice hulls and straw are reported. Alkali levels ranged from 0 to 100 g NaOH/100 g for hulls and from 0 to 50 g NaOH/100 g for straw.Effects of prior grinding, prior irradiation with gamma rays (0–50 Mrads), alkali reaction time (0–24 h), neutralization of excess residual alkali with acids, and rinsing effects were studied in terms of increased salt (ash) content, test material solubility in water and in vitro and in vivo (terylene bag) fermentation.Moderate increases in solubility and digestibility of straw followed irradiation but not for hulls. Major increases were found for irradiated straw further treated with alkali but hulls were little affected by 5 g NaOH/100 g D.M. except at the 50 Mrad level. Nutrient fortification of inocula media did not help dissimilation. Grinding had little effect on degradation of alkali-treated hulls. Straw responses were greater than for hulls.Alkali treatment removed encrusting silica and lignin from rice hulls and increased in vitro and in vivo digestibility. Above levels of 12·5 g NaOH/100 g dry matter in vitro digestibility was depressed unless residual alkali was neutralized. Alkali-treated hulls were reduced in silica content better by rinsing or by no neutralization and no rinsing: neutralization or neutralization followed by rinsing were less effective. Lignin was best removed by alkali or alkali and acid without rinsing. Alkali reaction time on hulls was not critical, but alkali concentration was.Animal trials indicated useful intake and digestive responses to alkali-treated rice hulls. Raw rice hulls were rejected by sheep.When fed in a mixed diet with lucerne chaff (40% whole rice hull, 60% lucerne chaff) daily voluntary intake of rice hull dry matter was 345 g (nil NaOH); 361 g (10 g NaOH/ 100 g rice hull); 193 g (20 g NaOH/100 g rice hull) with apparent dry-matter digestibility values for the hulls of 20%, 41% and 51% respectively.

Description: SummaryS. 24 perennial ryegrass, containing 2·9 g nitrogen/100 g D.M.〉, was conserved by freezing (to represent the fresh material) or by drying. Three dehydration treatments were imposed, comprising low temperature (inlet temperature 145 °C) high temperature (inlet temperature 900 °C) or oven drying (100 °C for 18 h) and in addition part of the high temperature dried grass was treated with formalin (1 g/100 g crude protein) prior to feeding.The digestion of the energy and nitrogen components of all diets was investigated using sheep fitted with re-entrant cannulae at the proximal duodenum and terminal ileum.Dehydration and formalin of the grass reduced nitrogen solubility and apparent energy and nitrogen (P 〈 0·001) digestibilities but led to increased quantities of nitrogen entering the small intestine (P 〈 0·01) compared with the frozen diet. A significant relationship describing nitrogen transformations was established: Y = 165–1·13X (r = –0·98, P 〈 0·001), where Y is g nitrogen entering the small intestine per 100 g N consumed and X is dietary nitrogen solubility. All dried diets showed increased losses of nitrogen within the small intestine compared with the frozen diet, the largest values being observed on the oven-dried and formalin-treated diets.Neither total VFA production within the rumen nor overall cellulose digestibility was influenced by dehydration, but on the formalin-treated diet there was a marked shift of cellulose digestion from the rumen to the caecum and colon compared with the other diets, associated presumably with the large reduction in protein solubility on this diet.Dehydration improved the efficiency of conversion of ruminally digested energy to VFA energy within the rumen, and in relation to the nature of the total absorbed nutrients a significant relationship was established:Y = 30·97–0·22X (r = –0·98; P 〈 0·001),where Y is g digestible crude protein lost in the total intestines per 100 g digestible organic matter intake and X is dietary nitrogen solubility.

Description: SummaryFourteen Friesian and 13 Angus steers, grown at pasture, were selected so that their carcass weights fell evenly throughout the range 200–300 kg. The right half of each carcass was dissected into muscle, fat, bone and fascia and tendon, and the left half boned-out and fat trimmed into retail cuts. A step-wise multiple regression procedure, including a pseudovariable for breeds, was used to compare compositional components on a common weight basis.Angus, at the lower end of the live-weight range, had heavier empty bodies than Friesians; at the heavier end of the live-weight range, this was reversed. This relationship between live weight and empty body weight was due to variation between breeds in the weight of contents in the fore stomachs but not the intestines.When compared at either the same live weight or the same empty body weight, Angus had more hot carcass than the Friesians (8·0 and 8·4 kg, respectively). There was no difference between breeds in loss of carcass weight in the 24 h post-slaughter.There was no breed difference in weight of blood, head, kidney and channel fat, kidneys, liver, diaphragm, heart, lungs, tail or fore-stomachs, when compared at the same offal weight. The feet and intestines were, respectively, 0·55 and 2·43 kg heavier for Friesians than for Angus at the same offal weight, but the pizzle was 0·11 kg lighter. Hide weight was greater in the Angus at all offal weights, with the difference between breeds being 0·016% of (offal weight).There was no difference between breeds in the weight of muscle or the weight of fascia and tendon when compared at the same dissected side weight; however, the Angus had 4·8 kg more fat and 3·0 kg less bone than the Friesians at the same dissected side weight.When compared at the same muscle weight the Friesians had 1·04 kg more proximal hind-limb muscles, 0·30 kg more proximal fore limb muscles, but 0·74 kg less abdominal muscles than the Angus. At all dissected muscle weights the Angus had a greater weight of muscles of the neck and thorax, and this difference increased with increasing weight of dissected muscle. The Friesians also had 1·52% more of their muscle as ‘expensive muscle’. There were no breed differences in the distribution of any other muscle groups.There was no breed difference in the distribution of dissected fat between subcutaneous and intermuscular depots when these were the only fat depots considered. However, when kidney and channel fat was included in the total dissectable fat of the carcass, Friesians had 22·4 % more kidney and channel fat, the same weight of intermuscular fat and less subcutaneous fat than the Angus at the same total dissected fat weight.Friesians tended to have more of their bone weight in their legs (humerus, femur, tibiar–tarsus, radius–ulnar–carpus) and Angus more in their thoracic region (thoracic vertebrae and ribs, scapular and sternum-costal cartilages).At the same retail side weights there was no difference between breeds in the weight of fat-trimmed, boned-out, retail cuts; however, the Friesians had 3·3 kg more retail bone than Angus, but 2·3 kg less fat trim and 0·46 kg less sausage mince.There was no difference between breeds in the distribution of retail bone or of fattrimmed, boned-out cuts between the forequarter and hindquarter. However, the Friesians had 13·2 % more fat trim in the hindquarter. Friesians had 0·27 kg more retail cuts located in the rump but 0·80 kg less in the loin, when compared at the same weight of retail cuts. Also, the Friesians had more of their retail cuts as topside, thick flank and foreshin. There were no other differences between breeds in the distribution of retail cuts.

Description: SummaryTwenty experiments between 1970 and 1974 tested the effect of spring applications of all combinations of five amounts of potassium (0–333 kg K/ha) and two amounts of sodium (0, 150 kg Na/ha) on sugar-beet yield, profitability and the amount of K and Na in the crop in mid-summer. The experiments were in commercial sugar-beet crops where soils contained little exchangeable potassium, most having less than 100 mg K/l in top soil. On average, sugar yield was greatest when 150 kg Na/ha plus 167 kg K was used, the fertilizer increasing yield by 0·71 t/ha. Response to this combination of K and Na fertilizers was 1·45, 0·57 and 0·22 t sugar/ha when the soil contained less than 60, 61–120 and more than 120 mg K/l respectively.From results of earlier experiments, it was thought that response to even a large amount of K without Na would be less than to Na without K because usually there is insufficient rainfall in the spring for maximum response to K. In fact, 333 kg K/ha increased yield by about the same amount as Na, probably because a large proportion of these experiments were made in wetter-than-average springs.The concentration of K in dried tops and roots in mid-summer increased linearly with soils containing from 40 to 120 mg K/l but when there was more K in the soil the concentration of K in the plants did not increase further. By contrast, the concentration of Na in plants did not reach a similar plateau. Whole plants in mid-summer contained between 128 and 251 kg K/ha and 42–102 kg Na/ha, depending on the fertilizer treatment. Recovery of applied K varied from 90% when small amounts were used on fields containing least K to about 20% when large amounts were given on fields containing moderate amounts. Recovery of Na varied from about 50 to 23%.The comparison of the financial return from using K alone or K plus Na showed that Na was essential for maximum profit. On average, the most profitable dressing of K gave a return of £14/ha whereas K plus Na gave up to £46/ha. On fields with least K, the corresponding results were £50 and £115/ha respectively. In relation to soil K, the most profitable application was 150 kg Na/ha plus about 150 kg K/ha on soils with 60 mg K/l or less, and 150 kg Na/ha plus about 75 kg K/ha on most other soils.

Description: SummaryExperiments made over a period of 3 years (1971–73) at Pantnagar, India, on the effect of plant density and spatial arrangement of a hybrid variety of maize (Ganga 2) and a local cultivar (Rudrapur) indicated that a density of (at least) 75000 plants/ha is necessary to obtain maximum grain yield. With increasing density from 25000 to 75000 plants/ha the date when 75 % of plants were silking was delayed 2–5 days and the percentage of barren plants increased from 1·7 to 28·7. In dense stands, grain yield of the hybrid variety was less affected by increasing row width from 60 to 90 cm than it was in the local cultivar.The average increase in yield with narrow (60 cm) row width as compared with wider (75 cm) row width was 6.8 % and it is argued that, in the context of the national need for increased food production, this increase cannot be overlooked.

Description: SummaryThe effect of a single injection of 100 μg prostaglandin analogue Cloprostenol, during the luteal phase of the oestrous cycle was examined for synchronization of oestrus, time of ovulation and embryonic viability in ewes.Following injection of Cloprostenol alone, 84% of ewes were detected in oestrus 29–48 h later. Pretreatment with PMSG increased the proportion of ewes in oestrus within 36 h. In these ewes 38% had begun ovulating 30 h after the onset of oestrus and by 36 h 87% had begun ovulating. Normal embryos of 8-cells to blastocysts were obtained from ewes given PMSG and Cloprostenol, and on transfer to recipient ewes, treated with Cloprostenol, all recipient ewes produced lambs.It is concluded that injection of 100 μg Cloprostenol is an efficient method of synchronizing oestrus in ewes and that normal embryonic development would be expected in mated ewes following this treatment.

Description: SummaryPot experiments in which cowpea and hyacinth bean were grown at 15–45% soil moisture showed that nodulation, nitrogen fixation and plant growth were poor at 15%. The weights of nodules and plants were lower in January (winter) than in June (summer). In June cowpea was more tolerant of dry conditions giving good nodulation at 25–35% whereas hyacinth bean required 35–45%.Under field conditions the number and dry weight of nodules were affected by the irrigation interval whereas plant growth was affected by the amount of water applied. Applying 75 mm depth of water every 7 days gave the best combination of nodulation and plant growth.

Description: Untimely ploughing and rotavation of a silt loam soil was found to increase bulk density, and mechanical resistance to a needle penetrometer probe, and to reduce air porosity. These effects were not found deeper than 8 cm, although measurements with a 13 mm field penetrometer probe indicated some increase in mechanical resistance down to 30 cm. The effect of untimely cultivations on soil conditions was small when compared with the effect of loosening by hand digging. This treatment reduced substantially the bulk density and mechanical resistance; it increased air porosity and moisture content of the subsoil. Although measurements of mechanical resistance with the laboratory penetrometer were 2·4 times those of the field penetrometer, there was nevertheless good correlation between measurements.

Description: SummaryFour groups of eight lambs, 4 months of age and reared parasite-free from birth, were used to investigate the effect of the intestinal parasite Trichostrongylus colubriformis on the intake and efficiency of utilization of food, using balance trial and comparative slaughter techniques. One group (CI) was killed initially as control. Two further groups (ALC and ALI) were offered ad libitum a complete ruminant diet. The ALI group was dosed orally each day for 14 weeks with 2500 infective larvae. Sheep in a further group (PF) were individually paired to members of the ALI group, and given the same amount of food as their pair. Balances of nitrogen, Ca and P and the digestibility of dry matter and energy were determined for the ALI and PF groups during weeks 6–7 and 12–13 and after 98 days of infection the sheep were killed. The bodies of these and the CI and ALC sheep were analysed for water, fat, nitrogen, Ca and P contents.Parasitism reduced food intake over the whole experiment by 9%, but had no effect on the digestibility of energy or nitrogen. At the first trial the N balances of the ALI group were inferior to those of the PF group due to increased urinary N excretion, but there was no difference at the second trial. Ca and P balances of the ALI group tended to be inferior to those of the PF group at both trials. The weight gain of the ALI sheep was only 50 % of that of the PF sheep with the same digestible energy and protein intakes. The protein content of the gain in empty body weight of the ALI sheep was 80 g/kg compared with 112 and 124g/kg in the ALC and PF groups, respectively. Possible causes of the poor protein anabolism are discussed.The gross efficiency of utilization of metabolizable energy for growth was calculated to be 13·3 % in the ALI sheep, compared with 26·2 and 24·2 % respectively, in the ALC and PF groups. It was not possible to determine whether this was due to change in maintenance requirement or in efficiency of fattening.The Ca and P content of the skeletons of the ALC and PF sheep increased by 55 % during the 98-day period, while no net change occurred in the ALI sheep. It was concluded that this was caused by an induced mineral deficiency resulting from parasitic damage in the small intestine.

Description: SummaryA series of five metabolism trials was made to determine apparent nitrogen digestibility and metabolizable energy (ME) contents of protein rich feedingstuffs. The mean nitrogen digestibilities of fish meal, groundnut, mustard, sesame and cottonseed cakes were 66, 69, 68, 57 and 40%, respectively. Corresponding values for metabolizable energy values were 1820, 2460, 2330, 1870 and 1530 kcal/kg, respectively. The metabolizable energy contents of coconut cake, niger cake and blood meal were 1190, 2360 and 2190 kcal/kg, respectively. The quantity of protein, its digestibility and crude fibre content in the cakes are the prime factors for this trend in MB. Simple and multiple regression equations were derived from biologically assayed metabolizable energy and chemically analysed energy-yielding nutrient contents of the feedingstuffs. The simple regression equation is:ME kcal/kg = 32·95 (% crude protein + % ether extract × 2·25+ % available carbohydrate)–29·20.The multiple regression equation is:ME kcal/kg = 370·29 + (24·47 × % crude protein)+ (65·77 × % ether extract)+ (44·07 × % available carbohydrate)- (8·15 × % crude fibre).The correlation coefficients of simple and multiple regression equations were 0·72 and 0·73, respectively, indicating that there is very little advantage for prediction in using the multiple regression equation. The usefulness of the equation for routine checking of poultry feeds for ME is apparent since the nutrients required to predict metabolizable energy can be analysed within a short period of time.

Description: SummaryMidas, a barley variety very susceptible to brown rust (Puccinia hordei), and two less susceptible varieties (Julia and Mazurka) were given three amounts of nitrogen (50, 100 or 150 kgN/ha) either at sowing (in March), in May, or half at each time. Benodanil sprays were applied to one half of each plot in June and again in July to control brown rust. Brown rust became more severe in 1973 than in 1974 and was most severe on Midas with 150kgN/ha. In 1973, there was most brown rust where all or part of the nitrogen was applied in May, but in 1974 there was least brown rust where all the nitrogen was applied in May, probably because dry weather limited its uptake.In 1973, when ample rain fell in spring and summer, grain yield was increased more by nitrogen given in May than in March, especially when benodanil was given. In 1974, little rain fell until July and then March nitrogen increased grain yield most whether or not benodanil was given. Top dressing of N (in May) produced a smaller straw yield than seed-bed dressing did in each year.Benodanil spray much decreased brown rust and increased yield of grain, but not of straw; the increase was greater in 1973 than in 1974, when brown rust was less abundant. Benodanil increased yields of all varieties, but that of the rust susceptible variety, Midas, most. Benodanil increased grain yield more, as more N was given to the barley, and more with N given in May than in March. It increased the amount of N removed by the barley grain, but not by the straw.

Description: SUMMARYPenned Romney wether sheep were fed ad libitum diets of untreated silage and hay made from the same pasture (Expt 1), untreated silage (Expt 2), and high quality fresh pasture (Expt 3). Voluntary intake and wool growth were measured. In each experiment half of the sheep were given intraperitoneal injections three times per week which supplied the equivalent of 1·03 g DL-methionine/day.Relative to silage in Expt 1, hay increased voluntary dry matter intake, depressed apparent nitrogen digestibility and increased wool growth. Methionine supplementation increased voluntary intake and wool growth with animals fed on hay or silage in Expt 1 and with those fed on silage in Expt 2, but had no effect on either variate with the diet of fresh pasture.Wool sulphur content, measured in Expts 2 and 3, was increased by methionine supplementation, and it was calculated that 34 and 15% respectively of the sulphur administered as methionine was recovered in the wool.The effects produced by methionine supplementation in this work are compared with those produced from different forms of post-ruminal amino acid supplementation in sheep fed a variety of diets. Factorial estimates of the requirements for sulphur of sheep and cattle in different physiological states have been calculated, and are discussed in relation to results of trials involving supplementation with sulphur-containing amino acids.

Description: SummaryA dynamic model has been derived to predict the day-to-day changes in the growth and nutrient composition of crops grown in the field with different levels of nitrogen and potassium fertilizer. Equations are included in the model to represent processes such as re-distribution of nutrients down the soil profile after rain or evapotranspiration, transformations between the various forms of potassium, transport of potassium ions through the soil to the roots and the dependence of growth and nutrient uptake on incoming radiation, plant composition, and soil water stress.The model was tested by using it to forecast the responses of a test crop, cabbage, to fertilizers in four separate field experiments at WeUesbourne. From data describing the initial soil conditions and weights of the plant, the soil and crop characteristics and the daily weather conditions, the model correctly predicted the pattern of responses in each experiment, although, in some instances the absolute values of the theoretical and experimental yields differed somewhat. Of special significance was the ability of the model to forecast the effects of different weather conditions on crop response and the interactions between the effects of N and K fertilizers on the growth and chemical composition of plants.

Description: SUMMARYChopped barley straw was fed ad libitum to penned Romney wether sheep. Supplements of urea, ground wheat grain + urea, lucerne hay and autumn saved pasture (ASP) were given for five periods each of 3 weeks using a 5 × 5 Latin square design. The latter three supplements supplied similar amounts of nitrogen and approximately 20% of the energy required for maintenance.The concentration of ammonia in the rumen fluid of sheep fed the basal straw diet was low and was increased by all the supplements. The concentration of total volatile fatty acids (VFA) in rumen fluid was unaffected by supplementation with urea, but was increased by the three supplements of nitrogen and energy. Differences in VFA molar proportions between treatments were small.Sheep offered straw alone had a digestible energy (DE) intake of 69% of maintenance and showed a weight loss of 121 g/day. Supplementation with urea had no effect upon apparent energy digestibility (42%) or voluntary intake, but significantly reduced the rate of live-weight loss. The lucerne hay and ASP supplements also had no effect upon straw consumption, but increased total DE intake to 87% of maintenance due to the additional energy provided by the supplements, and reduced live-weight loss. Supplementation with wheat + urea increased the estimated amount of digestible organic matter derived from straw by 8·5%, increasing DE intake to 94% of maintenance and reducing live-weight loss to 18 g/day.Averaged over all five groups of animals, straw intake increased by 9% in the second period of feeding and then gradually decreased with time, reaching a value in period 5 which was similar to period 1.

Description: SUMMARYThe experiment described was carried out to compare the effects of some combinations of dietary ingredients which were within the bounds of current commercial use but which differed in their lipid characteristics.The four dietary treatments used were either low or high in lipid content with a high or low proportion of unsaturated fatty acids in that lipid. Fourteen pigs (seven gilts and seven barrows) were assigned at random to each dietary treatment. The major dietary constituents were barley × wheat × dried skim milk (treatment 1), barley × wheat × soyabean meal (treatment 2), barley + wheat + dried skim milk × tallow (treatment 3) and barley × wheat × maize × fish meal (treatment 4).Production performances were satisfactory on treatments 1, 3 and 4. The pigs on treatment 2 ate less food, grew more slowly, had poorer feed conversion ratios and fatter carcasses than the animals on the other treatments; the reason for the poor performance on this diet is not clear.Comparison of the fatty acid compositions of the backfat triglycerides and the dietary lipid shows that the dietary lipid had little effect on the backfat lipid characteristics; only in the case of linoleic acid was there a dietary-induced effect on the amount of this fatty acid in the backfat triglycerides of pigs on treatment 4.Treatment 4 which produced the backfat with the greatest linoleic acid content also produced the softest backfat. The subjective fat scores of the carcasses of pigs fed the other diets were not related to the fatty acid compositions of the backfat triglycerides or the monoene/saturated fatty acid ratio.These results are discussed in relation to the effects of diet and triglyceride structure on pig backfat lipid characteristics.

Description: SUMMARYThree buffalo calves and four Holstein x Hariana cross-bred calves of 4–6 months of age were fed for 21 weeks either on a normal protein ration according to National Research Council (1966) standard or 25% below or above it. The scheme of feeding was as follows:Blood urea was determined every week from 6th to 21st week except in 10th, 14th and 15th week. When the animals attained the age of 15–17 months, their blood urea was again determined.Blood urea of buffalo calves was found to be significantly higher than that of cow calves under similar conditions of feeding from 4 to 11 months of age. This difference disappeared at 15–17 months of age. Probable causes for this difference between species are discussed. Blood urea in both species tended to increase on high protein and decrease on low protein rations.

Description: SUMMARYMeasurements of O2 consumption (Vo2), CO2 production (VCO2) evaporative water loss and rectal temperature (Tr) have been made and metabolic heat production (H), evaporative heat loss (—E) and respiratory quotient (RQ) calculated with individual and groups of 1-day-old chicks at constant ambient temperatures (To) in the range 20—43 °C and 80 or 20% relative humidity (R.H.).Minimal metabolism (10·7 kJ/kgJ/h) occurred at 35 °C.One-day-old chicks act as heterotherms outside the zone of minimal metabolism since neither H nor —E are sufficiently developed mechanisms to maintain homeothermy.Huddling allows chicks to maintain a higher TT at a lower H per unit metabolic body size.Reducing E.H. from 80 to 20% raised the upper temperature survival limit (UTSL) from 41·5 to 43 °C.Panting was initiated when Ta = 38 °C and Tr was between 39·5 and 39·9 °C.

Description: SUMMARYThe percentage of natural cross pollination was estimated in the Alexandria area (Egypt) in two sites near and far from an apiary. The Egyptian cotton variety Giza 45 and the glandless strain Bahtim 110, as a marker parent, were used during three growing seasons. The average natural crossing within the square of the marker parent were 3·54 and 0·34% near and far from the apiary respectively. For the plants around the square of pollen source, however, the average of natural crossing was 0·56% near the apiary, while it was 0·21% far from the apiary. The natural crossing steadily decreased as the distance from the marker variety increased.

Description: SUMMARYCarcass data for 424 castrated male lambs, comprising seven breed-type groups, were used toevaluate a series of linear measurements, subjective scores and the lean content of sample joints as predictors of percentage lean in carcass. The groups represented the main types of British lamb and mean carcass weights ranged from 12·8 kg (Welsh Mountain) to 20·8 kg (Lowland Longwool). Lambswere selected from commercial abattoirs to cover the ranges of fatness and conformation normally found in practice within each group. The pooled within-group S.D. for percentage lean was 3·70 and theoverall S.D. (ignoring groups) was 3·96.Predictors were compared in terms of precision and the stability of their prediction equations. Of the characteristics measured on the intact carcass, subjective scoring of external fatness gave the most precise prediction both within groups and overall (R.S.D.within = 2·82, B.S.D.overall = 3·17). Fat thickness over the eye muscle (0) was the best predictor among those taken on the quartered carcass (R.S.D.within = 2·76, R.S.D.overall =3·00). The most precise individual predictors were percentage lean in the best end neck and shoulder joints (R.S.D.within = 1·51 and 1·59 respectively). Among pairs of predictors not involving dissection, the combination of C and percentage kidney knob and channel fat in the side gave the most precise prediction (R.S.D.within = 2.51, R.S.D.overall = 2·68). The stability of the prediction equations between groups tended to increase with the precision of the predictors. Among the more precise predictors, the equation for percentage lean in the leg was a notable exception, being particularly variable from one group to another.

Description: SUMMARYThe grazing feed intake of four ¾ Brahman and four purebred Hereford steers was measured on four occasions during 12 months while they grazed improved pastures in a cool temperate environment. When pen fed roughage diets, the excretion pattern of chromic oxide and faecal nitrogen–digestibility relationships were also investigated in these animals.There were no breed differences in the relative recovery of Cr2O3 in the faeces when bulking 10.00 and 17.00 h samples nor were there breed differences in the faecal nitrogen–digestibility regression obtained. However, although there were large discrepancies between feed intake and live-weight change when measured in different seasons, the Herefords had the higher feed intake on each occasion while breed differences in live-weight change were non-significant.

Description: SummaryExperiments were made to assess the nutritive value of expeller-proeessed mustard cake (MS) for egg-type and meat-type chicks. Eight samples of MS on average contained 37·2% crude protein, 27·5% true protein, 12·6% available carbohydrate and 2·09 % tannins. The average metabolizable energy content (ME) of eight samples of MS for egg-type and meat-type chicks were 2350 and 2300 kcal/kg respectively. MS in the diet replacing groundnut cake (GN) which formed 30–32 % of the control diets was found to have no effect on growth rate of the chicks of either breed although there was thyroid enlargement. MS was also found not to affect the body composition of the chicks.

Description: SummaryExperiments were carried out at the Grassland Research Institute, U.K. (Expt 1) and the Universidad Central de Venezuela, Maracay (Expt 2), to study the influence of sward characteristics upon the herbage intake of young grazing cattle. In both studies the animals were strip-grazed in small groups on a series of plots, at a generous herbage allowance.The digestibility of the herbage ingested exerted a dominant influence on herbage organic matter (OM) intake, which increased at a constant rate as organic matter digestibility (OMD) increased throughout the range observed, 55–81% in Expt 1 and 53–63% in Expt 2. Intakes were similar in the two experiments at 60–65% OMD, but the rate of decline with decreasing digestibility was much greater in Expt 2 than in Expt 1.Intake was affected to a small extent in Expt 2 by the weight of herbage, the proportion of green material, and the extended height of the sward. In Expt 1 the intake from plots of primary growth was approximately 10% greater than that from secondary growths at equivalent digestibility and crop weight.The implications of these observations to techniques of grazing management are discussed.

Description: SummarySemi-purified diets containing urea (diet A), uric acid (diet B) or soya-bean meal (diet C) as the sole source of nitrogen were fed to two Friesian bull calves fitted with re-entrant duodenal cannulae. Total collections of digesta leaving the abomasum were made over 24-h periods.The flow of organic matter to the duodenum expressed as a percentage of intake increased from 35·8% (diet A) and 40·6% (diet B) for the non-protein nitrogen diets to 58·3% for diet C. A greater proportion of the apparent digestion of organic matter occurred in the forestomachs of the calves when fed diets A or B than when they were fed diet C.The flow of nitrogen from the abomasum expressed as a percentage of intake showed a significant increase (P 〈 0·05) from 65·4% for diet A to 84·4% for diet B and 85·1% for diet C. When diets B and C were fed to the calves a greater proportion of the apparent digestion of nitrogen occurred in the hindgut than when they were fed diet A. The synthesis of microbial protein was 13·9 g and 13·0 g for every 100 g of organic matter digested in the stomach when the calves were fed diets B and C and only 10·9 g when the calves were fed diet A.A significantly (P 〈 0·05) greater proportion of dry matter of the digesta at the duodenum was composed of amino acids on diet C (19·5%) than diet A (16·1%) with the proportion of essential amino acids (especially threonine, lysine, histidine and arginine) also being greater. The amino acid composition of the digesta dry matter on diet B was intermediate (17·2%).From the data presented, it was predicted that cystine and histidine were the first limiting amino acids for growth when the calves were fed the non-protein nitrogen diets (A and B).

Description: SummaryIndividual feed intakes of housed mature Greyface (Border Leicester × Scottish Blackface) ewes were adjusted weekly to maintain plasma 3-hydroxybutyrate concentrations during the final 6 weeks of pregnancy at the following values: treatment 1 (adequately nourished; 17 ewes) less than 0·7 mmol/1; treatment 2 (moderately undernourished; 15 ewes) at about 1·1 mmol/1; treatment 3 (severely undernourished; 15 ewes) at about 1·6 mmol/1.The mean energy intakes (MJ metabolizable energy (ME)/day) required to maintain the prescribed nutritional states in single- and twin-bearing ewes were: treatment 1, 14·3 and 16·3; treatment 2, 10·6 and 11·6; treatment 3, 8·1 and 10·0 respectively.The moderate degree of undernourishment had no significant effect on the birth weight of single lambs, but reduced the birth weight of twins by 8·2%, while the more severe undernourishment reduced the birth weights of singles and twins by 21·5 and 25·8% respectively.Foetal energy requirements, estimated by regression analysis, appeared to decrease from more than 2 MJ ME/kg/24 h at 35 days prepartum to 1·54 MJ ME/kg/24 h in the week before parturition.The amounts of energy required to sustain the nutritional states of treatments 1–3 in non-pregnant ewes were calculated to be 348, 271 and 231 kJ ME/kg0.75/24 h, compared with a maintenance requirement, determined in this experiment, of 344 kJ ME/kg0.75/24h.It is concluded that in individually fed ewes a nutritional state characterized by plasma 3-hydroxybutyrate concentrations of 1·1 mmol/1 would constitute an acceptable compromise between an uneconomically high energy input and an excessive reduction in lamb birth weight.

Description: SummaryThe effects on seed yield of two levels of water stress at four stages of development were investigated in two varieties of sunflower, Krasnodarets and Record. The plants were grown from seed in large pots in an air-conditioned glasshouse at 26/20 °C and 70% relative humidity, with natural summer illumination. They were subjected to water stress before head formation, during head formation, during flowering, and during seed development.The leaf water potential of plants subjected to a water stress of – 16 bars returned to normal after rewatering, but plants subjected to – 23 bars did not return to their prestress level and some leaves died. A water stress of – 16 bars caused no significant reduction in dry weight of the vegetative structures, but stress at all stages of growth reduced seed yield. A water stress of – 23 bars reduced both total dry weight and seed yield at all stages of growth, seed yield being reduced more by a stress of – 23 bars than of – 16 bars. Oil content was slightly reduced by water stress.Water stress during anthesis reduced sunflower seed yield more than during later stages of development.

Description: SummaryA study of the solitary parasitoid Microplitis rufiventris on larvae of Spodoptera littoralis showed that the age of the host at parasitization influenced the rate of development of the parasite, the percentage of parasitized hosts giving rise to mature parasite larvae, the number of moults subsequent to stinging, duration of larval instars, and the fecundity and longevity of the resulting adult parasites.

Description: SummaryMarked significant differences were found between the crossbreed means in the percentages of palmitoleic, stearic, octadecenoic and the ratio of palmitoleic to stearic acids and in the percentages of subcutaneous, intramuscular and internal fats.The percentage of carcass fats and age were strongly correlated with the acids palmitoleic, stearic (negative), octadecenoic and the ratio of palmitoleic to stearic. Covariance adjustment for percentage carcass fat and age made little difference to the significant differences of the variates which indicates that significant breed differences exist between these variates.

Description: SUMMARYThe residues from a continuous millet–maize rotation, grown at two levels of phosphate and two levels of nitrogen fertilization, were either burned and the ash incorporated; chopped and incorporated unburned; or completely removed. After 3 years, differences in soil organic matter were small and largely non-significant, but the ash treatment had minimized the general fall in soil pH, and the ash and the unburned residue treatments had both conserved topsoil exchangeable K and Mg, which, where the residues had been removed, had declined by 44 and 12%, respectively. Fertilizer effects were also significant; single superphosphate had increased exchangeable Ca and lessened the fall in soil pH; calcium ammonium nitrate had depleted exchangeable Mg generally and had lowered pH and exchangeable Ca particularly where unburned residues had been returned.A balance sheet of soil cations (0–30 cm), drawn up from soil and crop analyses and known fertilizer inputs shows, first, that whereas the calcium added in single superphosphate increased the exchangeable reserves of this nutrient, that added as calcium ammonium nitrate did not and must be presumed lost by leaching; secondly, the decline in exchangeable K where residues were removed was much less than the total crop removal, indicating a probable substantial release from non-exchangeable form.In the fourth season, treatment-induced soil differences, in particular the ratios between exchangeable cations, significantly affected the chemical composition of the maize test crop but not its final yield.

Description: SUMMARYLettuce obeys the Shinozaki–Kira relationship in which the reciprocal of plant weight is linearly related to plant density. The intercept (a) represents the reciprocal of the weight of an isolated plant and the slope (b) represents the reciprocal of yield/unit area at high densities (the ‘ceiling yield’). This work examines the time course of (a) and (b) in an ‘ideal environment’ in which water and nutrients are non-limiting, and the light/temperature regime is constant.Two pot experiments are described: the first showed that the growth of isolated lettuces follows a logistic expression, which can therefore be substituted for a–1 in the Shinozaki-Kira equation. It was then hypothesized that b–1, the ‘ceiling yield’ would be constant over time. This was confirmed by the second experiment, giving the equationw–1t = w–10 e1–kt × w–1max × bd,in which wt is mean plant weight at time t, w0 and wmax are the initial and final weights of isolated plants, k is the early relative growth rate of such plants, b–1 is the constant ceiling yield, and d is the plant density.Two examples of the use of the equation are given: one shows how it predicts the interaction between seed size and plant density within a species (subterranean clover): the other illustrates how it can be used to explain why lettuce growth appears to be log-linear against time whereas cereal growth is more nearly just linear.

Description: SUMMARYThe results of experiments in which Navy beans (cv. Purley King) were precision drilled at the beginning, middle and end of May in 1972, 1973 and 1974 suggest that the optimum time to sow is mid-May when soil temperatures at 10 cm depth have reached 12–13 °C. Earlier sowing usually led to a reduced plant stand and low yields whilst in 1972 and 1974, two exceptionally cool years, later sowing resulted in lower yields following a reduction in 1000-seed weight.Despite contrasting weather conditions acceptable yields of seed were obtained in all 3 years from mid-May sowings although cool wet conditions in the autumn of 1974 curtailed drying of the seeds below 30% moisture content. Accumulated temperatures (Ontario units) were successfully used to predict stages in crop development and the data used to demarcate the areas in England most suitable for Navy-bean production.

Description: SummaryA study was made of the birthcoat and the birth weight of Merino lambs, coarsewoolled Ossimi and the reciprocal crosses. The pre-natal maternal environment had a clear effect on the fineness of the birthcoat of cross-bred lambs born to Merino ewes (Ossimi × Merino) where 22·6% had fine arrays, whereas those out of coarse wool Ossimi dams (Merino × Ossimi) were all coarse like pure Ossimi lambs.Merino birthcoats were the most highly evolved, having the highest curly tip/precurly tip ratio, whereas the Ossimi were the least evolved. Ossimi × Merino lambs had more evolved birthcoats than Merino × Ossimi. CT/Pre-CT ratios were 1·00, 2·35, 4·41 and 8·06 in Ossimi, Merino × Ossimi, Ossimi × Merino and Merino lambs, respectively.Ossimi birthcoats had almost straight fibres. Merino × Ossimi showed a low incidence of crimp post natally, Ossimi × Merino exhibited more post-natal crimp and that in Merino predominant crimp occurred throughout.Strong (coarse) fibres were more frequent in Merino × Ossimi whereas Ossimi × Merino possessed higher frequencies of the less strong fibres and CT/Pre-CT ratio than the other cross. The difference between the two means of the crosses was highly significant in all fibre types.Lambs with strong fibre type arrays were heavier at birth than those with finer ones.

Description: SUMMARYGas liquid chromatography was used to investigate the influence of several T, S and unclassified cytoplasms on the fatty acid composition of oil from A632 and CrS4HLA maize seeds. The fatty acid compositions of the A632 and CrS4HLA seeds differed markedly from each other with respect to oleic and linoleic acids but were stable within each seed line with respect to all sixteen of the cytoplasms tested.

Description: SUMMARYThe effect of stage of harvesting on dry-matter (D.M.) yield and chemical composition of barley, wheat and the legumes common vetch (F. sativa), woollypod vetch (F. dasycarpa) and fodder peas (P. sativum) were studied in Cyprus under low rainfall conditions in a series of trials sown in four successive years. Cereals were harvested at the beginning of heading, 50% heading and the milk stage of grain, and legumes at three stages from preflowering to full pod formation, D.M., protein and digestible D.M. yields and percentage D.M. content increased with age, whereas percentage protein content and D.M. digestibility declined. Under moisture stress conditions before and during the harvesting period D.M. yields did not increase significantly with age. Protein content of cereals under low rainfall conditions was higher than that of cereals grown in the U.K. under higher N fertilization levels. Rainfall conditions affected drastically the performance of both cereals and legumes. However, average yields were satisfactory; the barley variety 628 gave 8·98 t/ha, the highest D.M. yield among all cereal and legume varieties.

Description: SUMMARYThe effect of soil salinity (ECe range 2–9 mmhos/cm) on the growth of and ion uptake by barley, sugar beet and broad beans (crops increasingly sensitive to salinity) was investigated in a glasshouse experiment.Barley and sugar-beet yields benefited from the added Na in the soil but broad beans were always adversely affected. Changes in growth and ion uptake are discussed in terms of Na:K synergism and antagonism.Sodium:potassium antagonism was observed in barley just after germination, and in sugar beet throughout growth, but not in barley at other growth stages nor in broad beans. Greater Na uptake promoted increases in dry-matter yields of all plant parts with barley and sugar beet, indicating that Na played a specific role in their metabolism. In sugar-beet roots, sugar concentrations and dry-matter yields increased with added Na by half as much more than without added Na, suggesting that Na is an essential nutrient.We conclude from our experiments that the effects of salinity caused by Na salts when water is not limiting, is related not only to plant species but also to their stages of growth.

Description: SUMMARYThe effect of six intervals between harvests and three levels of N application on the proportion and yield of green leaf, dead leaf, ‘stem’ and inflorescence was studied in four ryegrass (Lolium) varieties during a 30-week period in the first harvest year in a field experiment. In one variety, S.23, the ‘stem’ was divided into true stem, leaf sheath, unemerged leaf and unemerged inflorescence.There was a bigger yield of ‘stem’ and a bigger total herbage yield response to doubling the interval between harvests in S.321 and S.22 than in S.23 and S.24.In the absence, but not generally in the presence, of applied N, S.321 outyielded the other varieties. S.24 was particularly responsive to applied N, especially in terms of green leaf yield.There was a large positive effect on yield of doubling the interval (from 3, 4 or 5 weeks to 6, 8 or 10 weeks respectively) during the main period of stem development. During the subsequent period, however, doubling the interval produced very little extra yield of total herbage and reduced green leaf yield substantially.The percentage increase in yield due to the application of N progressively decreased as the interval was increased.Maximum net production of green leaf was obtained by harvesting every 4 or 5 weeks for most of the season, extending to 6 weeks at the end. Harvesting every 3 weeks, by comparison, resulted in a slightly lower annual green leaf yield, but with a distinctly higher proportion of green leaf in the crop.Applied N generally had little effect on the proportion of crop fractions, but reduced the proportion of green leaf and increased that of' stem' in S.23 and S.24 at the August and September harvests.

Description: SummaryA replicated trial of 18 families of Navy-bean breeding lines in the F4 generation was grown at Cambridge. The selection-index technique was used to investigate means of improving the efficiency of simultaneous selection for four criteria, namely yield, seed shape (numerical scores from ‘good’ to ‘poor’), early maturity and increased height of pod tips. Relative economic weights were chosen. The yield components and a range of characters describing plant type were measured making 15 characters in all, and combinations of these were included in 32 indices.It was predicted that simultaneous selection would be limited by adverse correlations between some of the four selection criteria, especially early maturity and height. The estimated efficiency of selection would hardly be improved by including information on the yield components. Combinations of the plant type characters, on the other hand, were predicted to provide considerable additional advance amounting to a 10% improvement when information on total number of nodes and inflorescences and hypocotyl diameter was included.It was concluded that the time involved in collecting yield component data would be better spent collecting information on a limited number of plant type characteristics in future trials, and that an ideal plant was one with reduced branching and a few heavily podded inflorescences borne on a tall plant with a strong base.

Description: SummaryConcentrations of serum lipids, concentrations and compositions of liver lipids, and ultrastructural composition of hepatocytes were measured in non-lactating cows following a 6-day fast. There was no change in the concentration of serum lipids due to fasting. The content of total lipid in liver (g/kg of liver wet weight) doubled due to an eightfold increase in triglyceride, a twofold increase in cholesterol ester, a fourfold increase in free fatty acid and a 50% increase in cholesterol. The composition of liver lipids (g lipid/100 g of total lipid) changed with an increase in the proportions of triglyceride and free fatty acid, a decrease in the proportion of phospholipid, and no change in the proportion of cholesterol and cholesterol ester. The ultrastructural composition of the hepatocytes changed in fasted cows with an increase in the volume density of cytoplasm occupied by lipid droplets and lysosomes and a decrease in the volume density of glycogen. The number of mitochondria per cell decreased and volume of individual mitochondria increased. The fatty liver induced by fasting non-lactating cows was chemically and morphologically different from the fatty liver induced by fasting lactating cows.

Description: It has been observed that there is an appreciable from the beginning of flowering till its completion percentage of flower shedding in pulse crops but and the total number of flowers shed was calculated, reliable data are lacking. Preliminary studies were, At maturity, the number of full-size pods per plant therefore, vindertaken to collect information on the was counted and the percentage of flowers shed extent of flower shedding in some kharif (rainy was calculated, season) pulses.

Description: SummaryDissection data for 753 steer carcasses from 17 breed-type × feeding system groups were used to examine the distribution of bone weight between 11 standardized commercial joints, and the prediction of bone content in side (half carcass) from the bone content of individual joints. Breed types included Ayrshire, Friesian, Friesian × Ayrshire and crosses out of Friesians by Angus, Charolais, Hereford, Limousin, Simmental and South Devon sires. Group means for bone weight in the side ranged from 14·9 to 21·0 kg with a pooled within-group S.D. of 1·97 kg.The increase in bone weight in each joint relative to that in the side was examined using the allometric equation. Pooled within-group growth coefficients (b values) were lowest for the leg (hind shin) and shin (fore shin) joints (b = 0·86 ± 0·02 and 0·94 ± 0·02 respectively) and highest for the sirloin (b = 1·10 ± 0·05).At equal total bone weight, there were significant (P 〈 0·001) but relatively small differences between groups in the weight of bone in each of the joints tested.Bone weights in the top piece, shin and coast joints gave the most precise prediction of bone weight in the side: the pooled within group residual standard deviations were 0·62, 0·67 and 0·71 kg respectively. The limited variation between groups in bone weight distribution was reflected in the robustness of common prediction equations across groups.

Description: SummaryA low phosphorus diet given to growing sheep in metabolism cages was supplemented with different sized fractions of either defluorinated phosphate or dicalcium phosphate. For material of particle size between 0·50 and 0·25 mm diameter, significantly less fluorine was present in the urine and more in the faeces of sheep given defluorinated phosphate than for those given dicalcium phosphate. The fluorine present in coarser defluorinated phosphate was of similar availability to that smaller than 0·50 mm. Finer grade defluorinated or dicalcium phosphates smaller than 0·25 mm diameter were not more biologically available in respect of either fluorine or phosphorus than those of particle size 0·50 to 0·25 mm. The availability of the phosphorus in defluorinated phosphate was reduced when material coarser than 0·50 mm was given to the sheep.

Description: When high rates of fertilizer N are applied to grass in an area of low rainfall, considerable amounts may be lost to drainage in the subsequent winter if the N is not fully utilized owing to dry soil conditions during the growing season (Garwood & Tyson, 1973). The data now presented were obtained from the lysimeters described in that paper. The soil is a sandy loam, overlying chalk. The swards of perennial ryegrass (Lolium perenne cv. S. 23) were cut four times each year. Two rates of N were applied as ammonium nitrate (Nitrana), 250 kg (LN) and 500 kg N/ha per year (HN). Two-fifths of this N were applied in March and one-fifth after each of the first three cuts.

Description: SummaryData are presented on the relationship between seed yield, its distribution and the duration of growth. A plant model is proposed to achieve earlier ripening as well as high yield. The possibility of achieving this model is evaluated.The F1 and F2 progenies of a complete diallel cross between seven inbred lines of field beans (Vicia faba spp. minor) were studied in order to elucidate the possibilities for breeding for earlier ripening without sacrificing seed yield. In a space-planted field trial the inheritance of and relationship among yield and earliness characters were examined.On average the F1 generation was superior to F2 in seed yield as well as earliness of flowering and ripening. General combining ability (g.c.a.) effects were highly significant for all the characters studied and very high narrow-sense heritabilities were found for most characters. Specific combining ability (s.c.a.) effects were significant for all characters except for number of inflorescences, and significant reciprocal effects were found for seed yield and date of anthesis.Because of the importance of g.c.a. effects, the phenotypic correlations were mainly determined by, and therefore similar to, the additive genetic correlations in showing a positive relationship between yield and the duration of pre- as well as postanthesis growth. However, a relatively strong negative non-additive genetic correlation was found between yield and duration of post-anthesis growth.Path analysis showed that 70–82% of the variation in post-anthesis growth was accounted for by the distribution of seed yield described by four yield components, thus supporting the hypothesis that the duration of post-anthesis growth is highly dependent on the distribution and size of the seeds.Two possibilities for breeding earlier-ripening, high-yielding cultivars are suggested: (1) exploiting hybrid vigour in terms of earlier ripening and (2) reducing the duration of post-anthesis growth byselecting for more seeds per pod and more pods per inflorescence.