ALBERT

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: 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: 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: 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.

Description: SummaryNine field experiments (1970–5) investigated the effects of single or split applications of nitrogen fertilizer in February, March, April and May to in situ sugar-beet seed plants in their second year's growth. All experiments were within commercial crops of existing multigerm and monogerm varieties grown on fertile, deep soils in south Lincolnshire, north Cambridgeshire and Northamptonshire and on shallow limestone soils in the Cotswolds.Yield of seed averaged over years and sites ranged from 4·3 to 4·6 t/ha and so was not affected by nitrogen treatments, which also did not noticeably delay harvest. The usable proportion of seed from multigerm crops was 350–650 g/kg, and from monogerm ones 90–200 g/kg but neither was affected by nitrogen treatment. Application of nitrogen in May reduced laboratory germination by about 3% and seedling emergence in the field by about 5 seedlings per 100 fruits sown. The proportion of single seedlings fmonogermity') was not affected by nitrogen treatments, although it was affected by the monogerm or multigerm nature of the crop. An attempt to assess seed vigour was made by determining average seedling weight when grown in the field in the year following harvest, but results were inconsistent. Leaf petiole nitrate concentrations declined progressively throughout the season, but were increased by about a quarterin the month following nitrogen application. At all times they were large and probably not limiting growth. The test had no value for predicting nitrogen application rates or times.In practice it appears that the spring top dressing of nitrogen fertilizer should be made as a single application at the end of February or as soon as possible thereafter.

Description: SummaryStudies were made on the effect of 50% reduction in daily water intake during summer on food intake, digestibility coefficients of the cell-wall constituents (CWC), nitrogen retention and water excretion in urine and faeces in the Marwari breed of sheep of the Rajasthan desert, India. The water-restricted animals consumed 54 and 42% less dry matter and digestible energy respectively than normally-watered animals. The digestibility coefficients of different CWC were apparently, though not significantly, higher in water-restricted animals. Throughout the study period, animals of both the groups, particularly the water-restricted group, remained in negative nitrogen balance. Moisture loss through the faeces was about 22% less in the water-restricted group than in the control animals. The water-restricted animals lost 21·1% of body weight in 23 days and these animals, when allowed water ad libitum, were able to recover 71·5 % of the lost body weight within 3 days.

Description: SummaryFeeding and balance trials with 32P were carried out to measure the true absorption of P in battery and broiler waste and to assess the risk of urolithiasis in sheep.Groups of six, 8-week-old Scottish Blackface lambs were given one of eight experimental diets containing barley and either 15, 30, 45 or 60% of dried broiler or battery waste. After about 12 weeks on the diet, balance trials with 32P were conducted on a sample of the female lambs from each dietary group. The phosphorus intakes ranged from 4·6 to 15·9g/day.Poultry waste was a good source of P. The proportion of dietary P absorbed by the lambs (A) ranged from 0·49 to 0·90 and was inversely related to the dietary intake of P (I). The relationship was A = 0·893 – 0·0219I. All lambs were in positive P balance (0·24–2·81 g/day), but only the bones from the lambs consuming the diets containing 45 and 60% broiler waste were not osteoporotic.All lambs absorbed more P than they retained and the partition of the excess between urine and faeces were very variable.No clinical cases of urolithiasis were seen, but uroliths were found at post-mortem. The incidence was highest in lambs consuming broiler waste and in lambs consuming the diets containing 15% poultry waste.

Description: SummaryThe codling moth, Cydia pomonella L., achieved four successive generations in Egyptian pear orchards in 1974. Indices of infested fruits showed four peaks of infestation; the first at the end of April, the second during the first week of June, the third during the first week of July and the last at the end of July.

Description: SummaryThe effects of the physical environment in Manitoba on the growth of Vicia faba minor cv. Diana were monitored during 1974–5. Seed yields and dry-matter production were considerably lower than have recently been achieved with similar varieties in Britain. Factors integral to the prairie environment are suggested to be the cause of this productivity differential. In particular, high soil moisture stress appears to be capable of severely reducing yields especially when experienced during the early phases of reproductive development. Satisfactory dry-mayEer production is not likely to be achieved if the seasonal soil heat accumulation (above 5 °C) is less than 1000 degree days. Low soil temperatures in the initial vegetative growth stage may also be responsible for the failure to achieve potential crop growth. Similarly high ambient temperatures (above 20°C) appear to be deleterious to crop growth.Field-bean heat units were defined to facilitate the examination of potentially useful atmospheric heat on crop growth.

Description: SummaryThe reproductive potential of a sheep system is much reduced by the failure of released ova to be fertilized and to survive to parturition. This paper looks at currently available information on fertilization failure and early embryonic deaths. Separate hypotheses are proposed for fertilization and for early embryonic mortality. For fertilization, the hypothesis is that a ewe that mates with a ram will end up with either all or none of her released ova fertilized. For embryonic mortality, the hypothesis is that the survival of a fertilized ovum depends only on how many ova were released with it and is independent of the survival or death of those released with it. A mathematical model is constructed on these hypotheses and its predictions are compared with published experimental results of other workers.

Description: SummaryThe effects of osmotic pretreatments were tested on the germination responses of oat and wheat grains. Temperature and duration of the pretreatment with polyethylene glycol (PEG) at two osmotic potentials (OP) were the experimental variables. The rate and synchronization of germination at 5–25 °C were significantly improved in both species by osmotic pretreatments compared with untreated controls. Maximum promotive effects were obtained after pretreatment periods of 6 and 4 days at – 10 bars at 5 and 10 °C respectively, and after 3 days at – 20 bars at 25 °C. Rapid and synchronized germination of seeds may be of advantage by minimizing their exposure to environmental hazards at early stages following imbibition and by allowing more favorable competition with other fast-germinating and growing species.

Description: SummaryDeterminations of sodium bicarbonate (pH 8·5) extractable P made on profiles of a sandy loam soil 7 and 8 years after fertilizer application to coconut in the Dry zone of Sri Lanka showed that the downward movement of P from concentrated superphosphate was greater than from rock phosphate (saphos). The surface layers (0–15 cm) of soil given concentrated superphosphate had higher P values (60 and 89 mg/kg for the 8th and 9th year respectively) than those given rock phosphate (3 and 16·5 mg/kg). At 40 cm depth the concentrated superphosphate treatment had 6 and 30 mg P/kg but the rook phosphate treatment had almost zero P at and below 40 cm.Phosphorus in the soil profile 8 years after fertilizer application was fractionated by the method of Chang & Jackson. Concentrated superphosphate treatment increased the Al-P and to a lesser degree Fe-P and Ca-P. Rock phosphate treatment increased the Ca-P and to a lesser extent Fe-P and Al-P. Phosphorus concentration in the 14th leaf was significantly correlated with Al-P, Fe-P and NaHCO3-P but not with Ca-P and organic P.The significance of the findings to phosphorus fertilizer application to coconut is discussed.

Description: SummaryRumen fermentation, duodenal digesta flow and N balance were studied in three sheep fed diets which contained urea or fishmeal as nitrogen supplement and either barley straw, barley + corn starch or molassed wheat straw (60% molasses) as carbo-hydrate source.The molar composition of rumen volatile fatty acids (VFA) with straw diets was high in acetate (64–68%), with barley diets high in propionate (32–36%) and with molasses diets high in butyrate (28–34%). Rumen ammonia concentrations (RAC) were low and constant with fishmeal diets (〈 10 mM) but varied with carbohydrate source with urea diets. RAC was very high (24 mM) after feeding molasses + urea.With barley and molasses diets 73–75% of digestible dry matter (DDM) was digested in the stomach, but only 54–59% with ground and pelleted straw diets. For all diets less N passed the duodenum than was eaten. The lowest daily duodenal N passage was with molasses + urea. Daily urinary N output was highest (P 〈 0·01) for this diet and nitrogen balance lowest.Daily intakes of amino acids differed widely between diets but differences in duodenal passage were not so great. Molasses + urea provided the lowest values for daily duodenal amino acid flow. The amino acid content of duodenal N (mM amino acid/16 g N) was relatively constant despite broad variation between diets. Digesta alanine and valine (mM/16 g N) were higher for barley than for straw diets (P 〈 0·05). Digesta methionine (mM/16 g N) was lower for fishmeal than for urea diets (P 〈 0·01).Very little sucrose reached the duodenum with any diet.It was concluded that the form of energy-yielding nutrient inuflenced duodenal N flow by affecting ammonia-N capture in the rumen, but that the amino acid content of duodenal N was little affected. The interaction between molasses and urea was not beneficial to efficient use of urea-N in this work when molasses was the major carbohydrate component of the diet.

Description: SummarySugar yield increases from irrigation in 19 experiments on a sandy-loam soil at Broom's Barn over an 11-year period were examined in relation to rainfall and to both potential and measured soil moisture deficit. Irrigation increased average yield from 7·6 to 8·3 t sugar/ha and in six of the years significantly increased yield by more than 1 t sugar/ha (15%). The experiments also tested plant density, nitrogen, harvest date and time and amount of irrigation. Without irrigation, maximum sugar yield was from a density of 74000 plants/ha but larger densities gave slightly more yield when irrigated. Irrigation affected the magnitude of response to nitrogen but 100 kg N/ha gave the most profitable yield increase, both with and without irrigation. Yield increases of about 1 t sugar/ha (15%) between early and late harvesting were also independent of irrigation. Early irrigation of 25 mm and 50 mm in June and July respectively increased yield in 4 of the 5 years but in all years applications in late summer did not increase sugar yield. The main factors controlling the yield response to irrigation were period and size of deficit. The soil type and summer rainfall at Broom's Barn were compared with those in 36 other experiments at five localities between 1947 and 1973; yield increases at Broom's Barn were smaller, probably because the others were on lighter soils.

Description: SummaryA digestibility and metabolism experiment was carried out to study the effect of two levels of feeding Rhodes grass-concentrate mixed diets when the grass had been preserved as hay or as frozen grass. Twenty Awassi lambs were used.The method of preserving the Rhodes grass did not affect the digestibility of dry matter, crude protein or nitrogen-free extract. However, the digestibility of energy and crude fibre was lower with the hay treatments.A consistent trend towards higher digestibility of the diets' constituents was observed with the high level of feeding.Acetic acid concentration in the rumen was lower with the hay than with frozen grass. Feeding the high level resulted in higher concentrations of volatile fatty acids in the rumen.A highly significant effect of the level of feeding on the C2/C3 ratio was observed; the high level of feeding resulted in a lower C2/C3 ratio

Description: SummaryRumen fermentation characteristics were studied using sheep fitted with rumen cannulae. Diets of 100% hay and 20% hay:80% cooked flaked maize (concentrate diet) were fed at the maintenance level of energy intake as two equal portions per day. Both the gas and liquid phases of the rumen were continuously sampled over 33-h periods.Concentrations of O2 and N2 in rumen gas inoreased during feeding, whilst concentrations of CO2 and CH4 decreased. Thereafter the concentrations of both CO2 and CH4 rapidly increased. The CO2: CH4 ratio increased rapidly following feeding; it declined to baseline levels 2–4 h after feeding the hay diet, but with the concentrate diet the decline took longer. O2 concentration declined rapidly following feeding and was stable within the range 1–3% for long periods. At no stage was O2 absent from the rumen gas phase. H2 comprised 100–1500 μ1/1 and 100–6000 μ1/1 of the gas phase in sheep fed the hay or concentrate diets respectively and its concentration increased very rapidly with the onset of eating. CO concentration varied between 2 and 16 μ1/1 in the rumen gas of hay-fed animals and was not related to time after feeding. In concentrate-fed animals CO comprised 0—130 μ1/1 of rumen gas and increased very slowly after feeding.Eh and rH values ranged between —150 and —260 mV and 8·0 and 5·0 units respectively for rumen contents from animals fed the two diets. A diurnal cycle was evident, with the most oxidizing state being attained just before feeding, and the most reducing state just after feeding. The diurnal cycles were better denned by rH than by Eh. The magnitude of the decrease in rH (and pH) during feeding was greater for animals fed the concentrate than the hay diet. At no stage during feeding did Eh or rH change towards more oxidizing conditions. Changes in the concentration of H2 in rumen gas were related to changes in the rH of rumen contents.VFA molar proportions showed no changes during the 24-h cycle with hay-fed animals but showed erratic variation with concentrate-fed animals. When two sheep fed the concentrate diet were sampled daily for 21 days, it was shown that VFA molar proportions were not constant.It was concluded that the gas phase of the rumen was never completely O2-free, and that whilst a stable rumen fermentation existed in sheep fed the hay diet the fermentation appeared to be continuously changing in the concentrate-fed sheep, and on this last mentioned diet abnormal values for rumen gas composition and VFA proportions were produced from time to time.

Description: SummaryGrain yield and incidence of take-all were measured in barley grown continuously and in successive barleys after two crops (oats, beans) not susceptible to the take-all fungus. Without fertilizer N, first barley crops after beans yielded about 1 t/ha more than second barleys and 2 t/ha more than third; growing more barleys did not further lessen yield. With increasing amounts of fertilizer N yields of barleys after barley nearly equalled yields of barley after beans. Take-all increased to a maximum in third barleys and was decreased by N, but it was not possible to separate the effects of take-all andsoil and fertilizer N on yield.

Description: Previous work has shown that the technique of laparoscopy in anaesthetized ewes is a practical and reasonably accurate method for the diagnosis of pregnancy between 17 and 28 days after conception and for estimating numbers of foetuses (Phillippo et al. 1972). This method in common with other reported endoscopic techniques for sheep positions the animal on its back, necessitating the use of either general anaesthesia (Roberts, 1968; Boyd & Ducker, 1973) or tranquillization and local anaesthesia (Kelly & Allison, 1976). These methods have the disadvantages of the necessity to withhold food and water for up to 24 h prior to surgery and the risk associated with general anaesthesia and the positioning of the animal. A new procedure with the sheep standing was therefore developed from the method used in cows (Mariana, 1969; Wishart & Snowball, 1973).

Description: SUMMARYThis paper reports a continuation of previous work on the mineral constituents of ewe's milk, in particular copper, iron, manganese and zinc. Milk taken at weekly intervals from four groups of Clun Forest and Suffolk x Clun Forest ewes was studied over lactations varying from 6 to 12 weeks. The copper content showed a marked decline as the lactation advanced, while there was no consistent trend in iron content. Maximum, minimum and mean values for iron and copper are given for the sheep in each group.Manganese was determined in the milk from two groups and zinc in. that from one group of ewes. There were significant differences in weekly manganese content in both groups, but no consistent trend as lactation advanced. Zinc content showed no significant differences from week to week, but the milk of one ewe was consistently very much lower in zinc than that of the other five sheep.

Description: SummaryThis paper presents the results of analyses of yield variability in more than 500 trials of varieties of spring oats, spring wheat, spring barley and winter wheat. A table of critical percentage yield differences has been constructed for guidance in planning future series of trials.

Description: SummarySugar beet bolting in the root crop was studied during nine growing seasons, under the extreme climatic conditions in which the autumn-sown crop grows in Southern Spain.Bolting is positively correlated with the number of days with minimum air temperatures ranging from 2 to 8 °C or with the number of days with mean temperatures between 8 °C and 13 °C.The occurrence of bolting is also affected by rainfall distribution in so far as it determines the date of seedling emergence.

Description: SUMMARYSowing date directly affected the grain yield of chick peas. Optimum sowing date was found to be between the end of October and the end of November, but different soil types showed some differences within this optimum.Grain yield was highly correlated with number of pods per plant and number of plants at harvest.Plant loss at the seedling stage was highly correlated with daily mean maximum air temperature, and was also significantly associated with sodium accumulation in shoots.

Description: Arginase (EC 3.5.3.1) catalyses the conversion of arginine to ornithine and urea, and is a key enzyme of the urea cycle. The enzyme is present in high activity in various mammalian red cells (Nishibe, 1973, 1974; Owczarczyk & Barej, 1975) and inherited arginase deficiencies have been found in two primate species (Shih et al. 1972; Terheggen, Lavinha & Colombo, 1972). The present paper describes an inherited arginase deficiency in the erythrocytes of certain sheep.

Description: SUMMARYIn a glasshouse experiment, fertilizer potassium and magnesium were applied in various amounts to 20 soils differing in the proportion of exchangeable potassium to the sum of the three exchangeable cations, potassium, calcium and magnesium. Maize, cv. Ganga-5, was grown as the test crop.In soils where the exchangeable cation ratio (K/Σ (K + Mg + Ca), in equivalents) was less than 0·025, potassium fertilizer significantly increased the dry-matter yield of maize. In soils where this ratio was between 0·026 and 0·05, application of potassium fertilizer was beneficial only up to the intermediate amount of 11 mg K/kg soil. Beyond this amount of application, addition of magnesium was necessary to increase yields. In soils where this ratio exceeded 0·05, potassium fertilizer reduced yields.An optimum ratio of exchangeable calcium, magnesium and potassium appears more important than their absolute amount. Magnesium application to high-potassium soils improved the cation equivalent ratio within the plant and the dry-matter yield.

Description: SUMMARYThe organic matter intake of two breeds of sheep grazing a dry medic pasture was estimated by five different methods. The methods used were the calibrated weight estimate for measuring available herbage before and after grazing; a total faeces collection and digestibility trial; a tritium dilution technique; an established ratio of dry-matter intake to water intake; and an estimation using established energy requirements and the estimated metabolizable energy of the pasture. All methods gave similar estimates. It was concluded that the tritium dilution technique was the most useful method and that the dry-matter intake to water intake ratio was the easiest technique to use. The relative merits of the different methods used are discussed. The maintenance requirement for grazing German Mutton Merino and Awassi sheep was found to be 0·64 MJ ME/day/kg W0·75. When both breeds were caged in an open field the maintenance was 0·37 MJ.

Description: SUMMARYSetts of white yam (cv. Ogojo) each weighing 225 g were planted in mid·February. They were double-harvested, first in early August, early September or early October, and second in early November. The control was single-harvested in early November. The later the time of the first harvest, the greater the first-harvest yield and the higher the percentage of mature and marketable tubers. Delaying the first harvest, however, led to decreasing yields from the second harvest. Double harvesting never gave a significantly higher yield than that obtained from a single harvest. When the first harvest was taken in September, the combined yield from double harvesting was significantly lower than that of the single November harvest. In a study of the effect of sowing date on yield, late planting (April) resulted in lower first harvest and total yields than early (February) planting, but the second-harvest yield was the same. Supplementary watering of early yam plantings did not markedly accelerate emergence or increase yield.

Description: SUMMARYA radiographic study was made of the skeletons of 216 Suffolk x (Finnish Landrace x Polled Dorset Horn) sheep foetuses of known gestational age within the range 50–145 days. They comprised 10 singles, 42 twins, 105 triplets, 44 quadruplets and 15 quintuplets.The ages at which the primary and secondary centres of ossification first appeared are presented together with a description of the normal pattern of skeletal development. Attention is drawn to the variations which are found from one foetus to another. The main anatomical features of ovine foetal bone development are illustrated by line drawings and charts.By anatomical grouping the number of ossification centres was reduced to 80, including 40 primary and 40 secondary centres. Scores were obtained for each foetus by taking the numbers of primary and secondary centres that were present as percentages of the possible totals. The primary score was linearly related to foetal age up to about 100 days, and the secondary score was linearly related to foetal age beyond about 100 days. The relationships to foetal weight were similar but less close.

Description: SUMMARYSeventy-nine Finnish Landrace x Dorset Horn ewes in lamb to Suffolk rams were used in a comparative slaughter experiment to assess the effects of numbers of foetuses on the growth of the products of conception. The mean number of foetuses was 2·7, with a range from 1 to 5. The ewes were individually penned and given a standard diet with metabolizable energy concentration 7·7 MJ/kg and N concentration 21 g/kg, rationed at 2 kg/day during the first month and 1·25 kg/day during the second and third. Allowances beyond that time were on two scales and depended on the number of foetuses being carried as diagnosed by radiography. The ewes were slaughtered between 50 and 145 days of gestation. The gravid uterus was dissected into foetal, placental, foetal fluid and empty uterus components. Equations were fitted to the weights of each component to describe the effects of stage of gestation, litter size and ewe weight. For the mean weight per foetus (Y, kg) the preferred equation isIn (Y)= 2·419–17·574e-0.01976t–00079ft+0–0046w,where tis the time in days from conception, / is the number of foetuses and wis the weight (kg) of the ewe at mating. This is a version of the Gompertz equation, with additional terms to express the effects of / and w.The weights of the placenta and of the empty uterus were similarly fitted by versions of the Gompertz equation but the mean weight of fluids per foetus (Z, kg) or, rather, its natural logarithm was best described by a third degree polynomial, which isIn(Z) = –11·518 + 0–326t;–0·00316t2+0·0000102t3.None of the weights was significantly affected by the level of feeding in late pregnancy.Estimates of mean weights from the equations and of daily rates of gain in weight from the first differentials of the equations are tabulated against stage of gestation and litter size, and the forms of the weight, growth rate and specific growth-rate curves are illustrated graphically.The equation for foetal weight estimates that at the end of pregnancy the mean weight per foetus is reduced by a factor of 0–89 for each additional foetus being carried. The mathematical model implies that the differences originate in early pregnancy, when the factor is very close to unity, and that the mean weights gradually diverge. In the absence of direct evidence this would appear to be the simplest hypothesis, rather than the assumption in most of the earlier literature that the effect is entirely confined to the last 4 or 5 weeks of gestation.Just before parturition the total daily weight gain of quadruplet foetuses was about 250 g and was associated with a similar gain in weight of foetal fluids, the ratio of fluid weight to foetal weight appearing to increase with litter size. The ewes were clearly under considerable physical stress. It is suggested that this aspect must be closely considered when greater prolificacy is sought.

Description: SUMMARYEight cultivars of peas (Pisum sativum L.) were evaluated for six traits in a diallel experiment using regression coefficients, correlations and combining ability estimates. Regression coefficient was high, indicating large additive effects for 100-grain weight. Yield was significantly and positively correlated with plant height, number of pods per plant and 100-grain weight, indicating that selection for either of these would result in higher yield. The best index of yield among the traits studied was number of pods per plant. Significant general combining ability (GCA) variances and specific combining ability (SCA) variances were observed. GCA variances were larger than SCA variances except for yield, suggesting predominance of additive gene effects.

Description: SUMMARYAn experiment is described in which plots of a silt loam soil and a clay soil were compacted by ploughing when the soil was ‘wet’ or ‘dry’. Further plots were thoroughly loosened by hand digging. These treatments resulted in a wider range of soil physical conditions than had been obtained in a previous experiment.A 2-year ley of Italian ryegrass was grown on the plots and was harvested twice in each year. Marked effects on crop yield were found at the first harvest but relative effects at subsequent harvests were much smaller. Yield responses to differences in soil physical conditions depended on stage of crop, levels of applied nitrogen fertilizer, inherent chemical fertility of the soil and distribution of rainfall during the growing season.

Description: SUMMARYThe total body water (TBW), its distribution and water turnover were measured in native fat-tailed Awassi sheep, a breed well adapted to desert conditions, and in imported German Mutton Merino (GMM) sheep, a breed that evolved in a temperate climate, under semi-arid conditions.TBW (tritiated water space;TOH space), extracellular fluid volume (SCN-space) and plasma volume (T·1824 space) were measured during the summer while these sheep grazed natural pasture that remained as dried stem-cured hay and in the winter while they grazed lush natural pasture. No differences were found between the breeds in any of the measurements in both seasons. Within both breeds, the percentage TOH and SCN-spaces were larger in the summer whereas the percentage T·1824 space remained the same.TBW and water turnover were measured in these breeds in eight trials while the sheep grazed native pasture in the autumn, winter and spring, shrubs in the winter and legumes in the summer. Water and shade were freely and easily accessible throughout the grazing period. The TBW was found to be consistently lower in the Awassi, indicating a higher energy reserve. The water turnover in 1/24 h/kg wt.0·82 was found to be higher in the GMM in all trials; the differences ranged between 3 and 28%. However, in only two out of the eight trials were the differences significant. Thus, the water turnoverwas only slightly lower in the Awassi although this breed evolved under Middle Eastern arid and semi-arid regions.

Description: SUMMARYThree herbicides, Treflan, Basagran and Avadex BW and three pesticides, Metasystox 55, Nicotine and Hostathion stimulated the growth of Fusarium solanif. sp. phaseoli in culture and increased the virulence of this pathogen on Phaseolus vulgaris. The implications of these results to the chemical treatment of this crop are discussed.

Description: SUMMARYThe artificial fibre bag technique was evaluated for assessing the proportions of dietary D. M. and N which disappear in the rumen. The most important factor determining the variability in disappearance from bags incubated together was the sample size in relation to bag size. For incubation of 5 g air dry feed, a bag size of 17 ✗ 9 cm was found to be adequate. There were also variations in substrate disappearance between animals and between days of incubation. It was estimated that three sheep and the measurement of substrate disappearance twice were necessary in order to obtain acceptable repeatability.The technique was found to be satisfactory as a simple and rapid guide for measuring nutrients disappearance in the rumen such as protein degradation and carbohydrate fermentation. It has been used in subsequent work to measure the effect of features of the rumen environment, such as pH and NH3 concentration, on rate of fermentation.

Description: SUMMARYThe production of toxic levels of ethanol in the stomachs of neonatal ruminants resulting from fermentation of glucose by resident yeasts occurs only in the absence of fat from the diet. Daily levels of ethanol and numbers of viable yeast were measured on samples of stomach contents for 21-day periods. Milk fat was shown to control the ethanol production in lambs and calves (but not in vitro in culture), the quantitative nature of this control was demonstrated by experiments with cream using lambs. Nine dietary fats in commercial use homogenized in fat-free milk, a commercial catering ‘milk’, and an intravenous lipid feed were all tested in lamb-feeding experiments, compared with whole and separated milk, and an inert oily hydrocarbon, liquid paraffin.

Description: Cassia acutifolia Del., known in the Sudan as ‘Senna Makka’ and in commerce as ‘Alexandrian Senna’ (Tothill, 1948), is indigenous to the Sudan and grows wild in the Northern and Central Provinces. It is used locally as a laxative and itsactive ingredient senoside is extracted for pharmaceutical purposes in England, U.S.A. and Germany. The Sudan has been exporting pods and leaves of Senna for many years and the crop has been steadily growing in economic importance. The exported produce is obtained from wild or cultivated Senna plants. Recently a breeding programme has been initiated to provide improved varieties that can both meet the growers’ need for high yield and satisfy the market's demand for uniform high quality produce. Before a proper plant breeding programme can be established, the mode of reproduction must be known since crop breeding procedures are largely determined by the reproductive system. This paper reports on studies made to determine the breeding system in Alexandrian Senna.

Description: SUMMARYFive cultivation systems for spring-sown barley were tested on a clay to sandy-clay loam for 4 years and their cumulative effects on soil and crop measured. Four primary cultivations in the autumn, shallow (7·5 cm), medium (15 cm) and deep (23 cm) tine cultivation and mouldboard ploughing (23 cm deep) followed in spring by secondary cultivations and sowing, were compared with direct drilling seed into uncultivated soil after controlling weeds with herbicides. At the same rates of seed and fertilizer for all systems, direct drilling and shallow cultivation yielded significantly less grain than deeper tillage in the second year only; over 4 years the differences in mean yield were small and non-significant. In terms of crop output per unit of implement net energy (estimated) direct drilling was eight times more efficient than ploughing.Direct drilling and shallow cultivation caused concentration gradients of ‘available’ phosphorus and potassium to form in the top soil. Soil strength and to a lesser extent bulk density were greater without than with cultivation but these changes had only a relatively small effect on root distribution in the profile. In untilled soil the proportion of the root system was less in the surface 2·5–12·5 cm and greater in the 12·5–32·5 cm horizon than in shallow or deep tilled soil.Mean nitrogen uptake by the crop in the third and fourth seasons was least in direct - drilled barley probably due to lower rates of mineralization of soil nitrogen in compacted than tilled soil. It was deduced that for spring barley the ‘yield plateau’ was the same for each system but that optimal rates of nitrogen would be higher for crops in untilled than tilled soils.

Description: SUMMARYGrowth and tuber yield of local sweet potato cultivars were compared during the 1974 and 1975 growing seasons. Three cultivars significantly outyielded the others. The cultivar effect was associated with differences in individual tuber weight, rate of bulking and percentage of total dry matter diverted into the vine or stem. Mean crop growth rate (C) and percentage of total dry matter diverted into the tubers were greater in the higher yielding cultivars and there was positive and significant correlation between Cand final total dry weight. Leaf area duration (D) was greater in 1975 than in 1974 but the differences between cultivars in D was not consistent. Higher yielding cultivars had significantly greater tuber/leaf ratio than the other cultivars.Bulking rate and tuber weight were positively correlated with tuber yield, while the percentage of total dry matter diverted into the vine was negatively correlated with tuber yield.

Description: SUMMARYWool production from different flocks of Ossimi, Rahmani and Barki Egyptian local sheep, raised at six different locations in the country was studied. Different genetic parameters for greasy fleece weight of the three breeds were estimated.Location was of significant effect on annual greasy fleece weight of Rahmani sheep only. With the adjustment for differences in yield percentages, differences in clean wool production from one location to another were slight for the three breeds. Age of ewe was of highly significant effect on annual greasy fleece weight.Heritability estimates of annual greasy fleece weight of the ewes were found to be generally low in the three breeds (range 0·00–0·34). The estimates differed markedly with age; those of the yearling fleece weight of Rahmani and Barki ewes were the highest, being 0–19 and 0–34, respectively.Repeatability estimates of annual greasy fleece weight were also low, being 0·11–0·04 and 0·29 for Ossimi, Rahmani and Barki ewes, respectively.Estimates of genetic correlation between yearling greasy fleece weight of the Ossimi and Rahmani ewes and their weaning and yearling body weights were high and positive. Those between annual greasy fleece weight of the ewes and their reproductive performance traits differed greatly in the two breeds.

Description: SUMMARYMetabolism trials were conducted with sheep to study the effects of conservation of herbage as silage, frozen or artificially dried grass upon the magnesium and calcium availabilities in the conserved products.When the diet was changed, approximately isomagnesaemically, from hay and barley to each of the conserved products, there was a highly significant (P 〈 0·001) decrease in the plasma magnesium concentration. However, the plasma magnesium concentrations of the ewes eating the artificially dried grass were significantly lower (P 〈 0·05) than the corresponding values when they ate the frozen grass or silage. No changes were seen in the plasma calcium concentrations.The apparent availability of magnesium in the silage was significantly higher (P 〈 0·05) than that in the frozen and artificially dried grasses. Also, the apparent availability of magnesium and calcium was lower in the dried grass than in the other two products, whilst the retention of both magnesium and calcium was significantly lower (P 〈 0–05) when the dried grass was eaten as compared with the frozen grass and silage. The percentage urinary loss of magnesium was greatest on the silage and least on the dried-grass diet.It was concluded that artificially drying grass caused a reduction in magnesium availability.

Description: SUMMARYObservations were made of the ages at first appearance of each pair of permanent incisors (‘eruption age’), and the time from first appearance to full eruption of each pair (‘eruption period’), for Large East African Zebu cattle (Boran). For females the eruption ages were found to be 108·5±9·9 weeks, 137·2±12·9, 165·7±15·8, and 200·9±18·2 for incisor pairs one to four respectively; for steers the figures were 104·3±7·9, 130·3±10·6, 154·6±13·2, and 180·9±14·0; and for bulls 103·3±8·6, 127·6±11·2, 151·0±12·9, and 181·2±15·7. Females were significantly different from steers (P 〈 0.01), but steers not significantly different from bulls, for all four incisor pairs.The distributions of eruption ages for each sex and pair can be considered as Normal for statistical purposes. There is a tendency for eruption to be asymmetrical after the first pair, with the right tooth preceding the left.Correlations of eruption ages between adjacent pairs are of the order of 0·80 for all pairs and sexes; they decrease progressively as pairs intervene to 0·55 for the first and fourth pairs. Partial correlations approach zero when any intermediate pair is held constant. These results indicate that the whole eruption process is highly interdependent.Evaluation of age grouping and estimations from the presence of incisors showed that this technique, although limited on its own, is still the best developmental trait for ageing. A steer with one incisor pair present had a probability of 0·108 of being the same age or older than one with two pairs. The ages of steers with one and two incisor pairs present were 115·7±12·05 and 140·7±14·27 weeks respectively.Heritabilities of eruption age, for the various incisor pairs, varied between 0·91±0·33 and 0·43±0·25 for females, and 0·87±0·37 and 0·11±0·59 for steers.Sources of environmental variation examined were variation between and within years, both of which were of the same order and a very small proportion of the total variation. The maternal environment had a small effect, probably specifically associated with milk consumption, which had a correlation of —0·22 for females and —0·12 for steers (P 〈 0.01) with the eruption age of the first incisor pair.Eruption periods for females were 5·1±2·8 weeks, 5·7±3·8, 6·8±4·5, and 8·8±5·6 for pairs one to four respectively; for steers 4·6±2·6, 4·9±2·9, 5·6±3·8, 7·2±5·3; and for bulls 4·9±2·2, 4·8±2·7, 5·7±3·8, 6·0±3·3. Females were significantly slower than steers (P 〈 0·05) for the first three incisor pairs only, while steers did not differ significantly from bulls for any pair.The distribution of eruption periods was positively skewed, and the correlations between pairs ranged between 0·0 and 0·35. Correlations of eruption ages and periods within incisor pairs lay between 0·50 and 0·95.Variation of eruption periods was not significant within years, but was between years, and arose almost entirely from the first two experimental years. The majority of the heritabilities approached zero.Growth rate differences probably accounted for the differences in eruption periods between the four incisor pairs and the three sexes. The cause of asymmetry of eruption was not the source of the variation in eruption times within incisor pairs, the first tooth consistently having a greater eruption time.

Description: SUMMARYBirthooat fibre types were investigated in Barki, Merino and their crosses. The halo hair grade was high in the Barki breed, in the Merino a wide range of grades occurred but the majority was low. A trend of a decrease in halo-hair grade and an increase in non-hairy birthcoats occurred with the increase of Merino proportion in the crosses. An anterior reduction in halo-hair density was encountered in all groups under study.Fibre type arrays were all coarse in Barki and ¼ Merino, the ¾ Merino had 50% fine arrays and 75% of the Merino arrays were fine. A trend towards a maternal influence on the birthcoat was observed in the ⅜ Merino and ⅝ Merino; more fine arrays were encountered in lambs born to dams with more Merino proportion.Within saddle and ravine arrays, CT/Pre-CT ratio was highly significantly correlated with the pre-natal check as indicated by Merino proportion.It was suggested, from the birthcoat studies, that ⅝ Merino might be the best combination in the Merino crosses as far as the fibre type arrays were concerned.Less coarse arrays were encountered in the birthcoat due to selection against kemp in rams used for breeding.

Description: SUMMARYField experiments, using Vicia faba cvs Herz Freya and/or Maris Bead were made in 1972–5. Population densities were varied and shading treatments were applied. Soil moisture content was monitored throughout. Maximum dry-matter production per plant and per unit area were similar in 1973 and 1974, but lower in 1975. Variations in growth were associated with variations in soil moisture content. When pods began to fill, plants reached maximum total water content and root growth ceased.Increasing density enhanced, and shading retarded both leaf senescence and seed maturation. Maximum potential seed yield (5–6 t/ha) in 1974 was obtained at 32plants/m2. In 1975, yields of 7–9 t/ha were obtained at 66 plants/m2, probably as a result of retention of many pods by the plants. Since total dry-matter production was lower in 1975 than in 1974 we conclude that photosynthetic potential did not limit yield in the earlier year.From the patterns of rainfall, soil moisture and plant water content, we suggest that water supply may be a more important factor controlling yield than either solar radiation or plant competition, with the period following pod setting being especially vital. At this time plant water requirement may often be in excess of supply.

Description: SUMMARYThree soya-bean (Glycine max L.) genotypes (Bragg, Type I and Hark) were grown in Mollisol supplemented with 0, 2·5, 5·0 mg Zn/kg in pot-culture experiments. The genotypes showed significant differences in their capacity to absorb Zn. Maximum Zn accumulation was found in the genotype Bragg and minimum in Hark. The pattern of Zn distribution in plant parts was also different in the three genotypes and was differently affected by Zn application. The uptake and percentage distribution of 66Zn followed more or less the same trend as that of total Zn. The genotypes differed significantly in R(recovery), A(availability of native Zn) and L(labile soil Zn) value indicating that these three genotypes differed in their capacity for recovering applied and native Zn. The genotype Bragg had maximum R, A and L values. These results correspond well with the reported tolerance of these genotypes to Zn deficiency (Bragg 〉 Type I 〉 Hark).

Description: SUMMARYThe mean concentration of plasma albumin in 30 Finnish Landrace x Dorset Horn ewes subjected to intensive breeding decreased as the number of pregnancies increased from three to seven; it also changed significantly within a pregnancy. Gamma globulin concentration was not affected by the number of pregnancies but decreased significantly within a pregnancy. Total plasma protein was affected like albumin by the number and stage of pregnancy.Plasma volume increased by 23 % in the latter third of pregnancy.

Description: SUMMARYTwo varieties of Lolium perenne, the diploid Hora and the tetraploid Terhoy were sown either as a pure stand or as a binary mixture on to the surface of multipots filled with a standard John Innes compost. Density of sowing was varied over the range of 16, 24, 36, 50 and 100 seeds/pot. There were four replicates. The pattern of germination was followed over a period of 14 days when it was found that (i) the varieties did not differ in their germination when grown alone, but in mixtures the diploid was slower to germinate than the tetraploid, (ii) as the density of sowing per pot was increased, the mean germination time (MGT) was increased, and (iii) the final germination of both verities decreased with increasing density.In a second experiment the same procedures were followed as before but seed of each variety was sown either as a pure stand or in a mixture of varying proportion as follows: 100:0, 75:25, 50:50, 25:75, 0:100.The results showed that (i) the diploid had the fastest MGT whilst the mixture values showed no significant variation, and (ii) the final germination percentage of the diploid decreased relative to its pure stand value as its proportion in mixtures decreased, whilst the tetraploid under the same circumstances increased relative to its pure stand value.It is suggested that differences such as those found could be explained by the presence of germination inhibitors in the seed coats of the two ryegrass varieties.

Description: Many authors have studied the follicle population in sheep and goats with a view to establishing a scientific basis for the breeding of sheep and goats with improved wool.Pant & Kapri (1966) examined skin samples from five Gaddis, ten Angoras seven F1S, eight first back crosses to Angora, four second back crosses to Angora and eight goats produced by inter se mating of the second back crosses and recorded the S/P ratio as 0·019, 6·55, 5·58, 6·25, 8·30 and 6·78 in the six types respectively. Das, Mitra & Nayudamma (1963) mentioned that the percentage of coarse hairs was about 35 in Indian goats. According to CLRI (1963) the density of hairs in Calcutta Black Bengal goats varies between 9000 and 13000/in.2 of the skin surface area and coarse hairs constituted about 28% of the total hairs. Ryder (1966) mentioned that the S/P ratio in Australian goats ranged from less than 5/1 to 7/1. He also noted the S/P value in Scottish goats as 3/1–5/1 and that in female Toggen-burg goats as 2·5/1–3·9/1. Sar & Calhoun (1966) reported that in Common American goats, three to six secondary follicles were associated with the trio of primary hair follicles. According to Burns (1965) the S/P ratio of Nigerian goats was 4/1. Margolena (1966) reported that in Texas and South African Angora does the primary follicles comprised about 9–14% of the total number of follicles. The purpose of this present investigation is to provide basic information on the S/P follicle ratio in Bangladesh Black Bengal goats.

Description: SUMMARYIn two experiments, 192 individually penned pigs were given diets containing 900 g barley/kg together with either 100 g dried microbial cells (DMC)/kg or 100 g white fish meal (WFM)/kg, and grown from 23 to 60 kg live weight. In Expt 1 rationing was by live weight and there was no difference between diets for feed used or live weight gained. In Expt 2, pigs were rationed by time and those fed diet DMC grew 15 g/day slower than those fed diet WFM, and their carcasses were of lower specific gravity.

Description: SUMMARYDigestibility trials were carried out to study the digestibility of Rhodes grass fed alone and in mixed concentrate diets. Twelve Awassi rams were used to examine the seasonal effect on the digestibility of Rhodes grass harvested at 21-day intervals.A consistent increase in the content of crude protein up to the 6th harvest was observed, being accompanied by an increase in crude protein digestibility and voluntary feed intake.In the second experiment Rhodes grass and concentrate mixed diets were examined. Sixteen Awassi rams were allocated to four diets which included 16, 32, 52 and 100% Rhodes grass. Dry-matter digestibility was found significantly different between the all-grass diet and the rest. The digestibility of crude fibre in the whole diet decreased significantly with the increase in concentrate content. The digestibility of crude fibre of Rhodes origin was calculated. It appears that the detrimental effect of concentrate on the digestibility of crude fibre of Rhodes grass origin is limited. This finding is supported by the high C2/C3 ratios in rumen liquor which were maintained up to 68% concentrate in the diet.This study indicates that Rhodes grass may serve as a highly efficient roughage component in dairy rations.

Description: SUMMARYThe digestibility of protein of mixed whole rumen bacterial cells and Streptococcus bovis were determined in Bos bubalis and goats. The bacterial cells were labelled either with 35S or 14C in vitro incubation and were injected in a single dose into the rumen after protecting by formaldehyde treatment. Faeces were collected for 6 consecutive days and radioactivity excreted in the faeces was measured. The digestibility of bacterial protein ranged from 81·7 to 96·8% in both the species.

Description: SUMMARYTwenty-one stocks of spring and •winter types of field bean were sown in April 1975 and 59 stocks of spring bean cv. Maris Bead were sown in March 1976, to investigate the relationship between seed germination and seedling emergence in the field. Laboratory germination percentage proved to be a very poor indicator of emergence in the field whereas the seed leachate conductivity test was a more useful guide. Even at recommended sowing rates low plant stands are shown to be a likely cause of yield loss and it is suggested that the conductivity test should be used to identify seed stocks of low vigour so that sowing rates of such stocks can be increased. It is recommended that the conductivity test be carried out as a useful adjunct to the standard laboratory germination test.

Description: SUMMARYThe growth, development and yield of three soya-bean varieties, Hampton, Kent and CNS, were compared in two field experiments during 1974 and 1975 in Nigeria. The results, which were similar for both years, showed that the varieties differed significantly in the order Hampton 〉 Kent 〉 CNS for the development per plant of leaf area, number of branches, number of nodes, number of mature pods, number of seeds, pod and seed yields, husk dry weight and seed to husk ratio as well as seed yield per hectare. The differences between the varieties in seed yield could be genetic but leaf area development seems important as well. Hampton therefore appears to have the potential for high seed yield under the prevailing local conditions.

Description: SUMMARYComparisons were made between cultivated safflower varieties (Carthamus tinctorius L.) and six wild ecotypes (C. oxyacantha Bieb.) for their tolerance to simulated drought conditions. Plant characteristics of the wild strains were noted and soil samples from their collection sites were analysed for the electrical conductivity of the saturation extract. Polyethylene glycol 6000, mannitol and sodium chloride were used as osmotic substrates to prepare aqueous solutions having 0, 1, 2, 5, 8, 12, 15 and 18 atm. of osmotic potentials (OP). The influences of treatments were studied on seed germination, shoot length and fresh and dry weights of shoots and roots of seedlings.Increased OPs progressively delayed and reduced seed germination, shoot length and fresh and dry weights of seedlings. Shoots were, however, more adversely affected than roots. Wild ecotypes were apparently more sensitive to high OPs than the cultivated varieties.

Description: SUMMARYIn a field experiment with 47 wheat genotypes, plant samples were taken at anthesis and maturity and analysed for nitrogen. Taking means over all genotypes, the plants contained at anthesis 83 % of the total present at maturity, while at maturity 68 % of the plant nitrogen was present in the grain.There was significant genetic variation in most of the component attributes determining nitrogen uptake. At anthesis, the heaviest plants contained most nitrogen. Because the nitrogen concentration in the leaves (average 2·8%) was much greater than in the stems and ears (average O8 %) and the leaves comprised, on average, 37 % of the plant weight at anthesis, variation in leanness was the main cause of variation in the nitrogen content of plants of a given weight. During grain filling, plants which lost the most dry weight from their stems and leaves took up the least nitrogen.It is suggested that the strong positive correlation between the accumulation of dry matter and of nitrogen, both until anthesis and during grain filling, occurred because both carbon assimilation and nitrate reduction depend on energy made available from chloroplasts. In addition, assimilate is required to sustain the growth of roots which is necessary for continued nitrate uptake.The results show that it should be easier for breeders to select for high nitrogen uptake from among heavy than from among light genotypes. However, although dwarf genotypes tended to be light, none of the correlations found was strong enough to render it impossible to produce dwarf genotypes capable of giving high yields of high-protein grain.

Description: SummaryThe drying rate of fully exposed individual lucerne plants was substantially increased following brief immersion in 0·18 M potassium carbonate solution. The increase was maintained over a range of drying conditions, and at low moisture contents, but the use of more concentrated potassium carbonate solutions yielded no further increase. Changes in leaf:stem ratio had a smaller effect on the drying rate of potassium carbonate treated lucerne than on untreated lucerne.Tests with diffusive resistance and viscous flow porometers support the hypothesis that potassium carbonate solution changes the water transmitting properties of the cuticular waxes.

Description: SummaryExperiments were made to evaluate the feeding value of undecorticated (UCS) and decorticated (DCS) cottonseed cakes and defatted DCS for egg-type starter, broiler starter and finisher diets for chicks. The results showed that UCS on average contained 22% crude protein, 0·06% free- and 0·33% bound-gossypol and 4·9% available carbohydrate. The corresponding values for DCS were 38, 0·04, 0·63 and 9·5%, respectively. Average metabolizable energy (ME) content of UCS, DCS and defatted DCS was 7·94, 11·77 and 9·42 MJ/kg, respectively. Apparent protein digestibilities of UCS, DCS and defatted DCS were 42, 47 and 36%, respectively. Although UCS had no effect on growth rate of egg-type and meat-type chicks when fed as 15% of the diet, feed conversion was adversely affected. Feeding DCS to broiler starter and finisher chicks as 30% of the diet, replacing groundnut cake (GN) had no effect on growth rate and efficiency of protein utilization but feed conversion was affected. The chicks of either breed were able to tolerate 0·02% free-gossypol of the diet derived from UCS or DCS without any adverse effect on growth rate and internal organs.

Description: In the winter-rainfall areas of southern Australia cattle and sheep grazing dry pastures in late summer and early autumn commonly lose weight because of a decline in the availability and nutritive value of the dry herbage (McLaughlin, 1973). Early-weaned calves and young lambs are affected more severely than older animals probably because of their low feed intake and their high requirements for energy and protein (Preston & Willis, 1970).

Description: SummaryMature cyclic ewes were treated intravaginally with sponges impregnated with 30 mg SC-9880 (G. D. Searle) or intramuscularly with 100 μg Cloprostenol (I.C.I. 80, 996) and examined subsequently for oestrus, ovulation and fertilization. At 70 h after the end of treatment, 90% of ewes treated with SC-9880 and 45% of those treated with Cloprostenol had ovulated. Of ewes yielding eggs at 100 h a significantly higher proportion of SC-9880 treated sheep showed evidence of fertilization (69% v. 7%).

Description: SUMMARYDissection data for 753 steer carcasses from 17 breed-type x feeding system groups were used to examine the prediction of lean content in the side (half carcass) from the lean content of standardized wholesale joints. Different prediction equations were examined and the joints compared both in terms of predictive precision and the stability of their prediction equations between groups.The relative precision of the joints for predicting weight of lean in the side depended on whether or not the prediction equation included joint weight. With side weight and weight of lean in joint as independent variates, there was little difference between most joints in precision, and the smaller joints, shin and leg (hind shin) appeared to be best because they are convenient and easy to dissect. The addition of joint weight to the equation improved considerably the precision of all the joints except the shin and leg. The coast and top piece gave the most precise predictions with the trivariate equation (residual standard deviations about the common regression line computed ignoring groups, RSD overall, were 1·44 and 1·48 kg respectively) and the fore rib probably offered the best compromise between cost and precision (RSD overall = 1·82 kg).The stability of prediction equations between groups was influenced in a similar way by the inclusion of joint weight as an independent variate. The joints which gave the most precise predictions tended to have the most stable equations. The average biases between the actual group means and the means predicted using the trivariate equation computed ignoring groups were ± 0·46, ± 0·49 and ± 0·76 kg for the top piece, coast and fore rib respectively.

Description: SUMMARYAn investigation was carried out to determine the daily energy intakes necessary to maintain, the live weights of ‘maintenance-stabilized’ steers (i.e. those held at constant live weight in pens for not less than 15 weeks) when walked at 5 km/h for distances of 5, 10 and 15 km/day.The experiment utilized groups of Boran Zebu and Hereford × Boran Zebu steers at live weights of 275 and 450 kg.Fed a standard diet of energy concentration 10·477 MJ metabolizable energy (ME)/kg D.M. it was found that the Hereford × Boran steers required significantly less food per day, at both live weights, than did the Borans to maintain live weight when walking distances of 15 km/day.Based on the data relating to the total distance walked of 1120 km in 133 days it was calculated that the additional energy cost of maintaining live weight when walking was close to 4·184 kJ ME/kg/km walked. The efficiency of conversion of ME for walking was 50%.For ‘maintenance-stabilized’ steers it was calculated that the 275 kg steers required 24, 49 and 73% more daily D.M. intake and the 450 kg steers 34, 69 and 97% more daily D.M. intake when walked 5, 10 and 15 km/day respectively than would have been the case if they had been kept inactive in pens.

Description: It has been shown (Gordon, 1975) that certain progestagens administered intravaginally can be highly effective in the control of oestrus, ovulation and fertility in ewes. Prostaglandin (PGF2α) when infused into the uterine vein ipsilateral to the ovary containing the corpus luteum has been shown to result in luetolysis and a return to oestrus in a high proportion of ewes (Hearnshaw, Restall & Gleeson, 1973). Synthetic analogues of PGF2α have also been shown to have a marked luteolytic effect in ewes (Baird & Scaramuzzi, 1975). Variable fertility has been reported following the use of prostaglandin or its analogue for oestrous synchronization (Jennings, 1975; Haresign, 1976; Fairnie, Cumming & Martin, 1976; Lightfoot, Croker & Marshall, 1976; Trounson, Willadsen & Moor, 1976). Low fertilization has been reported after the use of a prostaglandin analogue and artificial insemination at a predetermined time in ewes (Boland, Gordon & Kelleher, 1978). The purpose of the present experiment was to extend these observations, using a ram in natural service after employing a double prostaglandin injection regime or an intravaginal progestagen treatment for the control of oestrus in cyclic sheep.

Description: SummarySeven experiments carried out over 3 years investigated the effects of the date of defoliation of the seed crop and the storage temperature of the seed on subsequent sprout growth.The time of defoliation of the seed crop had a small, variable effect on the number of sprouts but with all varieties in every year, early defoliation gave the greatest total sprout length. The effect of later defoliation on sprout length varied according to the variety and the year. Most of the variation in total sprout length per tuber appeared to be attributable to differences in the date of dormancy break of the seed tuber.Storage throughout the winter at 15 °C gave fewer sprouts but a greater total sprout length per tuber than storage at 9 °C. A linear relationship between total sprout length per tuber and accumulated day degrees above 0 °C from dormancy break accounted for most of the variation in sprout length occurring in Désirée, Pentland Crown and Majestic as a result of storage at 9 °C and 15 °C for different periods of time.

Description: SummaryLucerne was made into ten silages using either a flail or a precision-chop harvester with application of formaldehyde or a range of rates of formic acid during harvesting. Amino-acid analyses were done on the silages and on samples taken from the herbage at ensiling.In excess of 70% of aspartic acid, serine, glutamic acid, tyrosine, threonine, lysine, histidine and arginine were destroyed in untreated silages when a flail harvester was used and in excess of 50% when a precision-chop harvester was used. Glycine, leucine, iso-leucine, valine and methionine showed little change, with net losses or increases of up to 10%, whilst proline, cystine + cysteine and phenylalanine were intermediate between these two categories. Net synthesis of alanine and α and γ amino-butyric acids occurred in the untreated silages. Increasing rates of formic acid addition, and the use of the precision-chop harvester, reduced the loss of the amino acids which were extensively degraded in the untreated silages and minimized the increases in alanine and α and γ amino-butyric acids. Formaldehyde treatment also reduced amino-acid degradation, apart from apparently high losses of lysine, histidine and tyrosine. It was concluded, however, that these losses arose through problems of estimation in formaldehyde-treated silages following HCl hydrolysis.It is suggested that the most probable precursors for alanine and α and γ aminobutyric acids were respectively aspartic acid, threonine and glutamic acid. Voluntary intake and the utilization of silage nitrogen by young sheep were related to the net changes in amino acids involved in decarboxylation reactions, the best measures of this being the interconversions involving the formation of alanine and α and γ aminobutyric acids. Deamination reactions appeared to be of much less importance in limiting silage nutritive value than those involving decarboxylation.

Description: SummaryIn two field studies it was found that lucerne hay swaths sprayed with 3000 1/ha of 2% (w/w) aqueous potassium carbonate solution after cutting dried more rapidly than mechanically conditioned or control swaths; the ratio of drying rates being 2·17:1·43:1·00 respectively. Hay yields were increased in one of the two studies by the use of potassium carbonate.The effect of different application rates was studied in a third trial using 200, 500 and 875 1/ha potassium carbonate solution, compared with mechanically conditioned and control swaths. After only 29 h of field exposure all swaths treated with potassium carbonate had dried to moisture contents below that required for baling (moisture: dry matter ratio 〈 0·3).

Description: SummaryFive male animals of each of the following species, zebu, eland, small East African goat, fringe-eared oryx and Dorper sheep, were penned, and their water intake measured and metabolic water production estimated. The figures for water input were compared with simultaneous measurements of body-water turnover by liquid scintillation counting of tritiated water in plasma, following dioxane precipitation. It was found that the resultant regression was sufficiently linear with the intercept near zero to justify the use of a ratio to predict input from turnover. The tritiated water turnover overestimated the water input by an amount approximately equal to the overestimate of the body water pool by the tritiated water space. Although there was a considerable amount of variation in individual ratios which could not be explained, there was no significant difference in the mean ratios between species.

Description: SummaryThe increase in dry weight of field lettuce from sowings made between March and August in 1973 and 1974 started exponentially but this did not persist throughout growth. Departures from exponential growth were most marked in the 10 days of growth prior to maturity and a logistic rather than an exponential curve gave a better overall fit to the data. The rates of increase in plant dry weight were similar from all sowings made between mid-May and early to mid-July, when air temperatures and total radiation during the growth period of these crops exceeded 11–12 °C and 250 mWh/cm2, respectively. Sowings made earlier than mid-May took longer to mature and in 1973 gave crops with lighter heads. Quadratic regressions of harvest date on sowing date gave good fits to data obtained in different years at different sites but separate equations were required for each site.

Description: SummaryGibberellic acid (GA3); monophenols, salicylic acid (SA) and β-naphthol (β-N); diphenols, catechol (CT) and resorcinol (Res); and polyphenols, chlorogenic acid (CA) and tannic acid (TA) hastened the emergence of ears and increased the numbers of branches and ears, number of seeds, seed weight and the 1000-seed weight in cheena millet (Panicum miliaceum L.). The results show that the action of phenolic compounds is not related to their structural configuration as is considered by some workers.

Description: SummaryA field experiment testing the effects of potassium and magnesium sulphates applied from 1960 to 1967 and sodium chloride applied in 1966 and 1967 on a range of crops (Bolton & Penny, 1968) was sown with ryegrass in 1967. Only basal N and P was given to all plots until 1971 when basal K was also applied. The experiment terminated in autumn 1974.Grass yields were increased by K residues for 3·5 years but overall yields became small due to K deficiency. After giving basal K, residual K no longer increased yields but did slightly increase % K in the grass until the end of the experiment. Some residual K from the 1960–7 dressings was found in the sandy loam soil after the final harvest.Magnesium fertilizer residues slightly increased grass yields in the 1967–70 period but not later. However, % Mg in the grass dry matter was increased by the residues for the whole 7·5 year period. Exchangeable Mg was also increased in soil sampled after the final harvest, especially in the 23–46 cm subsoil.Sodium fertilizer residues increased grass yields until the basal K was applied, especially on plots without added K. Significant increases in % Na in the grass and Na uptakes were detectable in all years, i.e. up to 7·5 years after the last Na application. This finding is contrary to most accepted views on the longevity of Na fertilizer effects and could be important in areas where sodium deficiencies in cattle and sheep occur.Increases in % Cl in the grass from the sodium chloride were only detectable in the first two cuts in the year following the final application.

Description: SummaryFour experiments with 133 piglets of between 21 and 55 days of age were used to examine, by slaughter and chemical analysis, the composition of the body of young pigs. Following removal from the sow, the lipid content of the empty body decreased from about 15 to 7·6%, and in the subsequent 4 weeks had recovered only slightly to between 7·7 and 10·9%; with the exception of pigs with a particularly high intake of energy whose 42-day lipid content had increased to 13·2%. Where Y3 was the lipid gain, X1 the digestible energy intake (MJ) and X2 the ratio of digestible energy to digestible crude protein (g), over all experiments Y3 = 7·83X1 + 4945X2−1260. There was little change in the protein content of pigs consequent upon the effects of either removal from the sow, pig age, diet type or nutrient intake. Over all experiments and slaughter weights; P = 0·164W−100, where P was the protein content of the body (g) and W the empty body weight (g). The efficiencies of conversion of digestible energy to energy gain in body protein and lipid were 0·36 and 0·33 respectively, associated with a constant (daily maintenance) term of 0·462 MJ ME/kg LW0·75. The low value for lipid is as would be expected for animals catabolizing lipid within the experimental period.

Description: SummaryField experiments were carried out in the early and late growing seasons in the rainforest zone of Nigeria to find out the relationship between lodging, morphological characters and yield of maize.Morphological characters associated with lodging were plant height, ear height and length of basal internode. There was a negative correlation between lodging and yield. Much of the lodging recorded, especially in the early growing season, was due to weak stems. Earliness, diameter of stem and leaf area had no relationship with lodging.

Description: SummaryWhen two species are interplanted the interpretation of experimental data presents statistical difficulties because the yields of the two crops will not in general be independent. It is therefore desirable to have a method that will both allow significance levels to be determined and give full importance to the treatment means of the two crops. It is shown that a bivariate analysis of variance can be carried out with little difficulty and precise tests can be based upon it. If it would be helpful to combine the two crops in any way, e.g. on the basis of calorific value or price, the task is readily accomplished.

Description: SummaryA dry-block digestion system suitable for the estimation of total protein nitrogen in plant material has been evaluated. The method was found to be as accurate as Kjeldahl flask digestion, required much less fume cupboard space and enabled samples to be dealt with in large batches through weighing, digestion and analysis. The batch size can be designed to be compatible with the autoanalyser capacity. These advantages result in more rapid analysis with less chance of errors and accidents. A 45 min digestion period was found suitable for several crop species of widely different protein content, only field bean seeds required longer digestion time. Using the technique described samples are digested at a relatively low temperature (330 °C) for a short time and digests do not solidify on cooling. The autoanalyser method for determining ammonia concentrations in barley and malt digests (Micheson & Stowell, 1970) has been slightly modified for use with the plant materials studied. The dry-block and autoanalyser system is rapid, precise and compact, requires small amounts of tissue and is suited to the routine analysis of breeding material.

Description: SummaryAutomatic mobile shelters were used to keep rain off a barley crop in a drought experiment. The treatments ranged from no water during the growing season to regular weekly irrigation. This paper reports the effect of drought on the harvest yield and its components, on water use and nutrient uptake.Drought caused large decreases in yield, and affected each component of the grain yield. The magnitude of each component varied by up to 25% between treatments, and much of the variation could be accounted for by linear regression against the mean soil water deficit in one of three periods. For the number of grains per ear, the relevant period included tillering and ear formation; for the number of ears per unit ground area, the period included stem extension and tiller death; for grain mass, the period included grain filling.The harvest yields were linearly related to water use, with no indication of a critical period of drought sensitivity. The relation of grain yield to the maximum potential soil water deficit did show that a prolonged early drought had an exceptionally large effect on both yield and water use.Two unsheltered irrigation experiments, also on barley, were made in the same year on a nearby site. The effects of drought on yield in these experiments were in good agreement with the effects observed on the mobile shelter site.When fully irrigated, the small plots under the mobile shelters used water 11% faster than larger areas of crop, because of advection. The maximum depth from which water was extracted was unaffected by the drought treatment. When 50% of the available soil water had been used the uptake rate decreased, but the maximum depth of uptake continued to increase.Measurements of crop nutrients at harvest showed that nitrogen uptake was large, because of site history, and that phosphate uptake was decreased by drought to such an extent that phosphate shortage may have limited yield.

Description: In three experiments with mixtures of barley and oats, a combination of Midas barley and Karin oats gave consistently higher yields than the mean of the components and slightly higher yields than the better component. The performance of this mixture was maintained over different sowing patterns and seed rates, but where sowing was arranged to give an advantage to one component of the mixture at the expense of the other, mixture yields were less than where both components were closely mixed.The increased yield of the mixture was attributed to the greater tillering of barley in mixture than in pure stand, brought about by less competition before heading, and to a higher weight per grain of Karin in mixture than in pure stand, a result of its greater height after heading and the favourable disposition of its panicles and upper leaves in the canopy.

Description: SummaryThe rectal temperatures of ten cows were measured each morning and their milk temperatures measured at each morning and afternoon milking for 40 days in order to study the value of these temperature measurements in determining the best time to inseminate, whether or not standing oestrus is exhibited. The best determination was based on the observation that a cow in oestrus had a milk temperature, taken at morning or afternoon milking, at least 0·1 °C higher than the corresponding temperature on any one of the previous 15 days. This method successfully detected 12 of 14 oestrous periods in the 10 cows (86%) and gave a false positive diagnosis on 6 days out of a total of 236 non-oestrous days (2·6 %).

Description: SummaryThe responses of Stylosanthes guyanensis (Stylo) to frequency and height of cutting and the effects of feeding increasing amounts of stylo meal on egg production, yolk vitamin A, yolk colour and percentage hatchability were studied. In the agronomic study, the higher the cutting height, the higher the total yield of dry matter, yield of crude protein, yield of carotene, percentage of crude fibre and the lower the carotene and crude-protein content. A highly significant correlation between the carotene content and crude-protein content (r = +0·91) was obtained.The addition of stylo meal as more than 10% of the feed significantly (P 〈 0·01) depressed egg production. On the other hand, yolk colour, yolk vitamin A status and percentage hatchability were significantly improved with the feeding of stylo meal.

Description: SummaryDuring the period 1962–73, the majority of the 92 lactations of imported British Friesian animals were initiated during the dry season (October–March). The following average values were obtained: lifetime number of lactations, 4·5; lifetime milk production, 9392 kg; age at producing first live calf, 39·6 months; milk yield of nine lactations, 2159 kg; lactation length, 336·5 days; daily milk yield, 6·3 kg; 305-day milk yield, 2012 kg; dry period, 173 days.Milk production was highest in the fourth lactation when the animals averaged 7 years old. Differences in milk yield among lactations were small. Peak daily milk yield was greatest in the third lactation and was reached within the first 21 days of each of the first four lactations. A second but lower peak with the highest milk production persistencies at a later stage of lactation apparently depended on feed availability. The 305-day milk yield was reasonably predicted from the 100- and 200-day yields.Lactations subsequent to abortions and stillbirths were slightly longer, gave less milk (P 〉 0·05) and were followed by longer dry periods than those initiated by normal births.

Description: With the development of effective methods of oestrus synchronization (Gordon, 1975), it is now possible to breed ewes at most times of the year. Encouraging conception rates have been reported following insemination (Colas & Brice, 1970; Colas et al. 1973; Gordon, 1975). A major disadvantage with the technique is the need to inseminate ewes twice at 10–14 h intervals. Because of the anatomy of the ovine cervix, it is not possible to deposit semen in the uterus as in the bovine. The present experiment was designed to compare a single or double insemination with natural service. Two types of inseminating gun were employed in an effort to deposit semen deep in the cervical folds.

Description: SummaryBlood samples were taken from 172 Friesian bulls during 1973–5 on three or four occasions. The bulls were in Milk Marketing Board cattle breeding centres in England and Wales and were from 1 to 14 years of age.The blood samples were analysed for packed cell volume, haemoglobin, erythrocytes, mean corpuscular volume and glucose, and samples of serum for the concentrations of albumin, total protein, urea-nitrogen, inorganic phosphate, Ca, Mg, K, Na and Cu.Packed cell volumes and haemoglobin and K concentrations were higher in bulls than those previously recorded in dairy cows. There were significant age relationships for packed cell volume, haemoglobin, albumin and globulin (P 〈 0·001), inorganic phosphate and erythrocytes (P 〈 0·01) and Ca and Mg (P 〈 0·05).Repeatability estimates were calculated and compared with estimates previously obtained for dairy cows.On the basis of improved contemporary comparisons of the bulls, there was a significant relationship between the average milk yield of a bulls daughters and the concentrations of urea, inorganic phosphate and K (P 〈 0·05) in the blood serum of the bull.

Description: SummaryIn t h e four production areas studied the gross energy contents of the biomass of the U.K. and Californian sugar beet crops were about 222 GJ/ha/year, while those for the Queensland and Transvaal sugar cane crops were about 682 GJ/ha/year. Recoverable sucrose constituted about 45% of the gross energy yield in the sugar beet crops but only about 29% in t he sugar cane crops, largely due to the bagasse (fibre) present in the cane. Since the sugar cane bagasse was used as fuel it provided nearly all the energy for the production of raw sugar from the sugar cane crops, but sugar beet by-products supplied no energy for t he production of sugar from sugar beet. This difference between the two species was the main reason why the support energy required for sugar production from beet, 28·8 GJ/t sugar, was greater than for production from sugar cane, 10·5 GJ/t sugar. The ratios, energy in refined sucrose:support energy required for its production, were 0·60 for sugar beet and 1·60 for sugar cane.The efficiencies of conversion of the photosynthetically active solar radiation incident on the crops into energy in biomass (excluding fibrous roots) were 1·2% for sugar beet and 2·0% for sugar cane. This difference in efficiency did not appear to be due to a consistent species difference in the proportion of t he radiation intercepted by the crops, and may have been a consequence of the more efficient photosynthetic carbon fixation mechanism in sugar cane than in sugar beet. The efficiencies of conversion of incident photosynthetically active radiation into energy as sucrose recovered from the plants showed no consistent difference between species and averaged 0·56%.

Description: Sesamum phyllody is a serious disease of sesame (Sesamum orientale L.). The disease is mainly spread by the leaf–hopper vector Orosius albicinctus Distant (Ghauri, 1966). The biology and bionomics of the hopper was worked out by Bindra & Singh (1970). The relative fecundity–cum–fertility and longevity of the hopper on the diseased and healthy plants were studied to supplement the existing information.

Description: SummaryAgricultural research now has a long tradition of being served by statisticians, both those who are professionally trained and others who (in no derogatory sense) may be described as amateurs because their primary scientific training is in some other discipline. This paper urges that, as part of good research management, more attention be given to the numbers of statisticians needed and the responsibilities they should undertake.Questions to be considered include not only ‘Who should analyse specified bodies of data?’ but also ‘Which data require full statistical treatment?’. Poor judgement here can mean that the pattern of statistical activity is governed by the forceful approaches of other scientists more than by the scientific content of a problem; moreover, statisticians may be left with no time for the vital tasks of collaborating with others in the planning of research and displaying initiative in new approaches to quantitative problems. Not all research institutes have yet made their statisticians collaborators and partners in research rather than technicians with sharply delimited duties.Agricultural statisticians today should be deeply involved in research in cooperation with other disciplines, as innovators in statistical technique, and to some extent in development of statistical theory. They must be encouraged to publish, as partners in research teams and individually, to produce and document computer programs that implement methods required in agricultural research, and to improve statistical understanding among their colleagues in other disciplines. They are scientists whose responsibilities and rights are equivalent to those of other disciplines but need to be interpreted in relation to the research role of their subject. This paper asks for their proper integration into agricultural research, and not for special privilege.

Description: SummaryHay was fed to an in vitro continuous culture of the rumen microbial population and to sheep kept in metabolism cages, and the effects of potassium chlorate addition on the rumen fermentation were studied. The compound was given for 8 days in vitro and for either 3 or 8 days in vivo.Potassium chlorate addition in vitro (13·7 mg/g hay D.M.) depressed the production of CH4 and acetate, had little effect on propionate production and caused a small increase in the production of n-butyrate and n-valerate. The treatment also depressed cellulose digestion and the concentration of DNA in fermentor liquor, but increased the CO2:CH4 ratio in fermentor gas.When given in vivo for 8 days at 6·7 mg/g hay D.M., potassium chlorate progressively depressed total VFA concentration in rumen fluid, had no effect on VFA molar proportions but caused a small increase in the CO2:CH4 ratio in rumen gas. When administered in vivo for 3 days at 14·4–15·3 mg/g hay D.M. the treatment increased the molar proportions of propionate and depressed those of acetate in rumen fluid without affecting total VFA concentration. There were considerable differences between animals in propionate response, and the maximum responses were generally obtained 2–5 days after dosing had ceased. Potassium chlorate addition also caused a temporary reduction in appetite with some sheep.It was concluded that potassium chlorate was toxic to the rumen microbial population when given for 8 days, but that large doses given over 3 days could be used to increase the ratio of propionic acid relative to acetic and butyric acids produced from the rumen fermentation.