ALBERT

Description: SUMMARYTwo experiments were conducted to study the influence of heat treatment of Vicia faba beans on the productive performance of laying hens fed diets containing large proportions of the beans. In the first experiment, the effects of extruding and pelleting the beans were studied while in the second experiment the effects of autoclaving at 121 °C for 30 min the cotyledons and hulls of the beans were evaluated. Hyline-W36 layers were used in the first experiment while two strains (Shaver-288 and Dekalb) of birds were used in the second experiment. Each experiment lasted 5 months during which data on egg production, egg weight, feed intake, mortality and body-weight gain of birds were collected. The results obtained indicated that heat treatment (extruding, pelleting and autoclaving) of the beans, cotyledons and hulls had no beneficial effect on the productive performance of laying hens fed on diets containing large proportions of the heated beans, cotyledons and hulls. Egg-size reducing factors appeared to be concentrated in the cotyledons rather than the hulls of the beans.

Description: SUMMARYExperiments were made over a 3-year period in order to evolve a production package for yam that would eliminate the laborious operations of hand weeding and staking. First, nine herbicides were applied to yam plots before or after yam emergence. On the basis of weed control effectiveness and low phytotoxicity to yam plants, ametryne (2-(ethylamino)-4-(isopropylamino)-6-(methylthio)-S-triazine) was chosen for subsequent experimentation. Next, ametryne at 2, 4 or 6 kg/ha was applied to yam plots either immediately after planting, or with 1 kg/ha paraqviat (l, 1'-dimethyl-4,4'- bipyridinium ion) 3 weeks after planting. The delayed applications gave more effective weed control and higher yields than the early applications. For the delayed application, 4 and 6 kg ametryne/ha did not give significantly different yields, but yielded significantly more than 2 kg/ha. When a combination of ametryne at 4 kg/ha and paraquat at 1 kg/ha was applied 3, 6 or 9 weeks after planting, the weed control effectiveness was greatest at 6 weeks after planting while the 3- and 6-week applications did not give significantly different yields. Herbicide applied 9 weeks after planting gave the poorest weed control and the lowest yields.Finally comparisons were made between the conventional staked, hand-weeded yam production, and a new production package in which the yams were not staked and weeds were controlled with ametryne (4 kg/ha) + paraquat (1kg/ha) applied at or just before emergence. When small (150g) setts were used, yields from the new package were not significantly lower than those from the conventional system, even though the new package was considerably less laborious. Cultivation with large setts, however, resulted in a decrease in yield when the plants were not staked. Strategies that could further enhance the attractiveness of the new production

Description: SUMMARYThe effects of N, P and K fertilizers on the yield and N, P and K contents of grass cut for conservation, measured during 1958–63, were again measured during 1964–7. Grass given 38 kg N/ha per cut needed 31 kg K/ha per cut for full yield, grass given 75 or 113 kg N/ha per cut needed twice as much K. With sufficient K, at least 75 kg N/ha per cut was justified. The grass responded little to P.Percentage N in the grass, though greatly increased by N fertilizer, was little altered by K fertilizer. Percentage K, whilst greatly increased by K fertilizer, was decreased by N unless 62 kg K/ha per cut also was given. Percentage P in the grass was little increased by P fertilizer.Exchangeable K in the surface soil (0–20 cm) was maintained with time where the grass was given either 38 kg N plus 31 kg K or 75 kg N plus 62 kg K/ha per cut, corresponding to an N:K ratio of 1:0·82. Percentage K in the grass decreased with time throughout. Whereas a N:K ratio of 1:1·66 best maintained % K in grass during 1958–63 it was no better than an N:K ratio of 1:0·82 during 1964–7.Although exchangeable Mg in the surface soil decreased markedly between 1958 and 1967 (Mg fertilizer was not applied), % Mg in the grass did not. Mg in the grass was increased by N, but decreased by K fertilizer, and exceeded 0·2% (in dry matter) only in 1967 and then only where 75 or 113 kg N/ha per cut was applied.

Description: SummaryLive weight and total body water (TBW; measured as tritiated water space) were measured in eight pregnant cross-bred beef cows from the 6th month of gestation to approximately 1 month after calving. Using the values from these measurements and by estimating foetal, foetal fluid and foetal membrane weights from previously established prediction equations, the maternal live weight, maternal body water and maternal body solids were calculated.Live weight, TBW, maternal body water and maternal live weight increased during gestation, whereas maternal body solids decreased. The TBW percentage of live weight increased from 74·8 to 79·6% during gestation and remained at about 79·5% during the first month of lactation.It was concluded that live-weight changes alone could be misleading in assessing the energy balance of pregnant ruminants not only because of development of the foetus and associated structures but also because of maternal hydration.

Description: Alternaria blight of sunflower caused by Alternaria helianthi (Hansf.) Tubaki and Nishihara is the most important disease of monsoon-grown sunflower crops in India (Kolte & Mukhopadhyay, 1973; Narain & Saksena, 1973). It is also reported to occur in Rumania (Hulea, Iliescu & Bunescu, 1975), Tanzania (Allen, 1974) and Brazil (Ribeiro et al. 1975). The present studies were carried out to assess the effect of different disease intensities on yield and oil content of the sunflower crop.

Description: Seed potatoes are grown on the high plateaux of northern Israel where it is cool enough for a summer crop. The seed are used for winter production of ware potatoes in southern Israel. Irrigation is essential because of the arid summers. It is customary to apply much of the N fertilizer through the irrigation system in numerous small doses. Total N rates have ranged between 300 and 400 kg/ha. In 1975 various aspects of N, P, K fertilization for seed potato (Solanum tuberosum L., var. Up-To-Date) production were examined. There were no responses to P or K fertilizers so only the N fertilizer responses are reported here.

Description: SummaryThree experiments, each with six lactating Mehsana-Surti buffaloes, were conducted to investigate the effect of supplementary feeding of concentrates on intake of basal rations of berseem hay, maize silage or wheat straw and on the total intake of feeds in 3 × 3 latin square designs.In the berseem hay experiment, concentrate feeding at 16·8 or 26·1% of hay drymatter intake (DMI) resulted in a decrease of hay DMI by 0·77 and 0·65 kg/kg concentrate D.M., respectively. Intake of total digestible nutrients (TDN) and digestible crude protein (DCP) of buffaloes receiving concentrates in addition to hay were not different from those receiving hay alone. The possibility of some chemical factor limiting feed intake has been indicated for these rations in buffaloes. Supplementary feeding had a little effect on milk production.In the maize silage experiment, concentrate feeding at 14·5 and 27·7% of the silage DMI resulted in a similar increase of total DMI, thereby increasing the TDN intake and DCP intake. Appreciable increases in milk yield and solids-not-fat (SNF) content due to supplementation were noted, although milk-fat content tended to be low.Voluntary intake of rations comprising wheat straw fed free choice with three levels of concentrates at 28·7, 48·0 and 68·8 % of straw DMI was studied in the third experiment. Concentrate supplementation had little effect on straw DMI with the result that intakes of total D.M., TDN and DCP on the medium and high proportions of supplements were higher than those on the low proportion. The milk yield, of buffaloes receiving medium and high proportions of concentrates with wheat straw increased significantly over those receiving the low proportion of concentrates. The SNF and milk-fat contents were similar on all the three treatments. The implication of physical factors limiting intake is discussed in the case of maize silage and wheat straw diets.The lactating buffaloes failed to maintain their weights on either sole berseem hay or sole maize silage rations. Supplementary feeding helped buffaloes to register small weight gains on hay rations and substantial gains on silage rations. The buffaloes on wheat straw fed with three proportions of concentrates tended to put on a little weight. Multiple regression using pooled data of Expts 1 and 3 showed that the partial regression coefficient of metabolic body weight (kgW0·76) on TDN intake was not significant but that of 6% fat-corrected milk on TDN intake was, suggesting a close relationship between milk yield and food intake.

Description: Sesame (Sesamum indicum L.) is a crop of great antiquity which is widely grown in tropical and subtropical regions of Asia, Africa, South and North America and to some extent in Russia for edible oil and for animal feed purposes. The average yield in India is only about 235 kg/ha. Even under good management practices the seed yields usually remain poor and, therefore, commercial prospects of sesame production are not good.

Description: Agri-silviculture is the simultaneous husbandry of forest tree crops and food crops. In the first 1–3 years of forest crops such as teak, pine and Gmelina arborea, they are interplanted with food crops such as yam, maize and cassava in plantation. In humid countries such as Nigeria and Burma agrisilviculture evolved out of the needs to boost food production and satisfy labourers who work on afforestation programmes.

Description: SUMMARYFishmeal, soya-bean meal and urea were compared as nitrogen sources in diets rich in fibre for yearling cattle, using feeding trials and digestibility and nitrogen retention studies. All animals were individually fed. Diets supplemented with fishmeal supported the highest rates of daily live-weight gain and nitrogen retention. There was no response in dry-matter intake and digestibility from extra nitrogen, either from fishmeal or urea, when the crude protein of the diet was 8·5% or over, and a small response in digestibility when soya-bean meal was used.Molar proportions of VFA, rumen NH3-N concentrations and blood urea nitrogen concentrations were all affected by both amount and source of nitrogen supplementation. Multiple regression analysis showed the undegradable protein supply to be more critical with high than with low fibre diets.

Description: SUMMARYIn a field experiment in the north-west region of Tasmania, poppies (Papaver somniferum L.) were harvested at weekly intervals beginning 10 days after full bloom and continuing until 4 weeks after the dry commercial harvest stage. At each harvest the plants were cut off at ground level and partitioned into terminal capsules, lateral capsules, seed and the combined stem plus leaf component.The dry-matter yield of total plant and of all the components except seed achieved maximum values 2–3 weeks after full bloom and then progressively declined. For the total plant this decrease between maximum dry weight and that at the time of commercial harvest (8 weeks after full bloom) amounted to 26% while for terminal capsules it was 37% for lateral capsules 15% and for stem plus leaves 39%. In contrast, the dry-matter yield of total seed rose to a maximum by 4 weeks after full bloom and then remained constant for the duration of the experiment.The morphine concentration of both terminal and lateral capsules reached a maximum value of 1·1% 6 weeks after full bloom and then decreased by about 10% at the dry harvest stage. The morphine concentration of stem and leaves also reached a maximum of 0·1% about the same time as capsules but decreased rapidly and had halved by dry commercial harvest. The mutually compensating factors of decreasing dry-matter yield and increasing morphine concentration gave similar total plant morphine yields at any time of harvest from 2 to 7 weeks after full bloom. The morphine extracted from the whole plant at these times of harvest was about 50% greater than that derived from capsules alone at the time of dry commercial harvest.

Description: SUMMARYDNA and protein concentrations were measured in selected muscles from foetal and neonatal pigs; the protein: DNA ratios of hind-limb muscles were similar to those of the forelimb from 83 days gestation to 27 days after birth. The ratios increased during the perinatal period, providing evidence that maturation of muscle began in the last few days of pregnancy. RNA concentration, cathepsin D activity and tritiated thymidine incorporation were measured in muscles from the neonatal animals and the results indicated a surge of biosynthetic activity in the first days of life. Values obtained from the hind- and forelimb muscles were similar throughout the period of study with RNA: DNA ratio, cathepsin D activity and thymidine incorporation reaching maximum values at 4 days of age. A considerable proportion of thymidine incorporation was attributed to the mitotic activity of satellite cells.

Description: SUMMARYAqueous glutaraldehyde, in the presence of wetting agents Tween-20 or Haemosol, reacted with fresh cut lucerne (Medicago sativa L.), complete reaction being obtained with about 7·2 g (72 mmol)/kg herbage, or 18g/100g crude protein. Reaction with 25% w/v aqueous glutaraldehyde sprayed on to fresh lucerne was rapid, and at the rate of 66 mmol/kg lucerne, all aldehyde had reacted in 3 h and about 60% of the soluble leaf protein became insoluble. Formaldehyde at twice the molar concentration of glutaraldehyde was absorbed rapidly, but a longer time, up to 24 h, was required for the protein to become insoluble. Treatments with 22, 44 and 66 mmol glutaraldehyde/kg lucerne, and 44, 88 and 132 mmol formaldehyde/kg showed that reaction with leaf protein was approximately proportional to the amount of aldehyde. A major effect on the leaf cells was the fixation of chloroplasts, and intact fixed chloroplasts were isolated from treated lucerne with high protein: chlorophyll ratios of 5·8:1 to 9·5:1.Two varieties of lucerne, Kabul and Europe, pot-grown in a controlled environment cabinet, reacted rapidly when sprayed with glutaraldehyde and in 3 h soluble leaf protein was reduced from 30 to 16–17% of the total N. The plants rapidly lost water and the dry matter of the leaves rose to 42% for Kabul and 45% for Europe in 24 h. Stems showed little effect. Field spraying of lucerne with glutaraldehyde similarly fixed soluble leaf protein and caused desiccation of the leaves, rising to 47–50% D. M. in 3 days. The stems were little affected and subsequent regrowth of the plants was not inhibited.Feeding glutaraldehyde- and formaldehyde-sprayed lucerne to rumen-fistulated cattle showed that release of soluble leaf protein into the rumen fluid was greatly reduced, mean values being 40 and 43% respectively of the values obtained when control lucerne was fed. Mean ammonia concentrations were similarly reduced to 49 and 33% of the control values. Formaldehyde-treated lucerne, even after reaction for several days, frequently showed toxic effects on rumen micro-organisms, particularly protozoa. Glutaraldehyde reacted more rapidly with herbage and no toxic effects were observed. Both glutaraldehyde- and formaldehyde-treated lucerne were highly palatable to cattle.

Description: SUMMARYThirty-six mature Finnish Landrace × Dorset Horn ewes, each suckling two lambs, were used in a comparative slaughter experiment to measure changes in body tissues during early lactation. Two levels of body fatness at lambing were established by giving ewes a complete diet containing 10 MJ metabolizable energy (ME) and 139 g crude protein (CP)/kg d.m. either close to requirements or ad libitum during the second half of pregnancy. In lactation half the ewes in each group were given a complete diet containing either 90 (diet A) or 60 (diet B) % milled hay ad libitum. These diets contained 7·9 and 9·2 MJ ME and 121 and 132 g CP/kg d.m. respectively.Ewes fed at the two levels in pregnancy contained 8·4 and 19·6 kg chemically determined fat 5 days after lambing but had similar amounts of body protein, ash and water. Over 6 weeks of lactation ewes given diet A lost 60 and 69% of these weights of fat respectively, while ewes given diet B gained 5% and lost 30% respectively. Up to 26 g of body protein was lost daily from ewes given diet A but none from ewes on diet B. During early lactation the weight of the empty digestive tract increased while the weights of most other body components, particularly the carcass, decreased. The ratio of body energy change to live-weight change varied from 24 to 90 MJ/kg. Thus live-weight change did not accurately reflect relative or absolute changes in body energy.Voluntary food intake was greater for ewes given the high-energy diet (B) than for those given diet A and was depressed in the fatter ewes. Differences in intake could be explained by the effects of body fatness and diet on the weight of gut contents. Milk yield was not significantly affected by body fat reserves but was higher on diet B than A. Fat content of milk was higher and protein content lower for ewes with the higher fat reserves at lambing.As the contribution of fat loss to energy available for milk synthesis increased there appeared to be a reduction in the energetic efficiency of milk synthesis. A number of possible reasons for this are discussed.

Description: SUMMARYEwes in body condition scores of 2·4 (thin) or 3·2 (fat) on a 5-point scale and suckling twin lambs were grazed at two stocking rates for the first 16 weeks of lactation. Paddocks were grazed for periods of 2 weeks at densities of 80 and 160 ewes/ha in weeks 1–8 and then 70 and 140 ewes/ha in weeks 9/16 of lactation.Intakes of herbage by ewes were not significantly affected by body condition. Estimation of milk yield by weekly measurement of secretion rates over 4 h failed to demonstrate significant differences due to body condition except in weeks 9, 11 and 12, although there was a tendency throughout for fat ewes to produce more milk. However, the daily growth rates of the lambs during the first 8 weeks and the overall live-weight gains were significantly higher for lambs suckled by fat ewes than for those suckled by thin ewes. Intake of herbage by lambs was not affected by the body condition of the ewes.Herbage intakes, milk yields and lamb growth rates were all significantly higher at the low stocking density than at the high stocking density.

Description: SUMMARYAll the pods on pigeon-pea plants were removed after 1, 2 or 3 weeks of flowering in a pot experiment and in one field trial, in order to evaluate the compensatory ability of the crop under humid tropical conditions.Pod removal after 1 or 2 weeks of flowering led to an immediate significantly higher vegetative development and dry-matter accumulation compared with the control. Subsequent flowering led to greater pod production and pod yield than the control with seed yield increased by 21 and 50%, respectively, in the pot experiment while pod removal after 1 week of flowering increased seed yield by 15% in the field. The removal of pods after 3 weeks of flowering was detrimental to subsequent pod development and seed yield which was decreased by 56 and 34% in the pot and field experiments, respectively.It would seem that the loss of pods produced soon after flowering starts, before active pod filling begins, can be tolerated by pigeon peas, whereas the loss of fully elongated and actively filling pods would significantly reduce seed yield in the crop.

Description: SUMMARYRadiological examinations were carried out on ten sheep to see what changes in intestinal motility and flow of digesta were caused by intestinal cannulation. Barium sulphate was injected or infused into the abomasum via an implanted catheter; its passage through the intestine and associated muscular contractions were observed using X-ray image intensification. Once the normal pattern had been established for each individual, single or re-entrant cannulae were inserted into one of four positions in the small intestine.All the cannulations caused some disruption of the normal flow of digesta, causing retention of digesta and distension of the intestine around and proximal to the intraluminal flanges of the cannulae. The duodenum was affected the most, particularly by one type of re-entrant cannula which reduced the degree of jejunal filling; peristaltic contractions often failed to propagate beyond these cannulae and also caused some retrograde movement of digesta between the cannulation site and the duodenal bulb during the irregular contraction phase (ICP) of the migrating myoelectric complex (MMC). These re-entrant cannulae also impaired the clearing effect of regular contraction phase (RCP).

Description: SUMMARYThe efficacy of estimates of gut contents and total body water in increasing the precision with which the chemical composition of the body could be estimated in early lactation was evaluated in 36 Finnish Landrace × Dorset Horn ewes. The ewes were fed at two levels in pregnancy, and, in lactation, given diets of two metabolizable energy concentrations.The allometric relationships relating weight of chemical fat and protein to emptybody weight were not affected by treatment or stage of lactation. Inclusion of an index of gut contents, based on dry-matter intake, indigestibility and retention time of food residues, together with live weight in a regression equation predicting weight of body fat, only slightly increased the precision of estimate compared with equations using live weight alone.There was a close negative relationship between the proportions of water and fat in live weight. Inclusion of weight of body water with live weight in a regression equation predicting weight of body fat markedly increased the precision of estimate and the residual error (0·81 kg) was similar at different stages of lactation. However, when deuterium oxide space was used instead of body water there was only a small increase in precision of estimate and the residual error varied from 5·3 kg in early lactation to 2·1 kg in mid-lactation. The relationship between deuterium oxide space and body water was shown to be variable and altered by stage of lactation, and these differences were associated with differences in rate of water turnover in the animal's body.It is concluded that estimates of body water are unsuitable for estimating weight of body fat in early lactation.

Description: SUMMARYThe effect of level of N fertilizer on the composition, yield and quality of 21 crops was studied in experiments on adjacent sites of the same field to aid in the development of fertilizer recommendations.Yield of each of the crops first increased and then either remained the same or declined with further increases of N fertilizer. Interpretation by means of a simple model enabled response curves to be characterized by two parameters; one representing the beneficial component of the response and the other the detrimental component. Both varied greatly from crop to crop.The magnitude of the beneficial component of the response of most non-leguminous crops was largely determined by the potential demand of the crop for nitrogen; the exceptions were some root crops which responded less than would be expected on this basis. The adverse component was serious with root crops and those crops that are in the soil for only a short period. High levels of N increased the ratio of foliage to storage root dry weights even when total dry matter was unaffected. The changes were associated with a considerable increase in the % N in the dry matter of the roots.When crops were grown with their optimum levels of N fertilizer a simple linear. relationship between the mean %N in the dry matter and the total weight of dry matter per unit area covered all crops. Simple relationships also existed between total dry matter of non-leguminous crops and (a) the amount of N taken up by the crop from unfertilized soil, (b) the recovery of added fertilizer by the crop and (c) the beneficial component of the response of crops harvested before October.Percentage N in the dry matter at harvest was not a sensitive indicator of the extent to which plant growth was restricted by lack of nitrogen; a difference of 0·1% N in the plant material was associated with a 10% increase in yield.N fertilizer levels influenced the % dry matter and the incidence of crop disorders such as rotten roots and tissue discoloration, but the effects were seldom appreciable with practicable levels of fertilizer application.

Description: SUMMARYTwo semi-dwarf and two conventional height European spring wheat varieties were grown at different sowing dates and sowing rates in two dry years. Yield component analysis showed the varieties to fall into three groups. The conventional height varieties were dependent for grain yield on either a high number of ears or a large number of spikelets per ear whereas the semi-dwarfs were dependent on high spikelet fertility.The semi-dwarfs were consistently higher yielding over a range of environmental conditions than the conventional height varieties. Maintenance of high yield was associated with high spikelet fertility and 1000-grain weight, characters determined late in development. It is suggested that the change to the semi-dwarf plant type has resulted in high yields with greater consistency over a range of environmental conditions particularly when dry.

Description: SUMMARYA study was carried out during three successive years from 1970 to 1972 on different wool types. Breed groups involved were Merino (M), coarse-wool Barki sheep and five of their crosses. Traits studied were greasy-fleece weight, clean-fleece weight, kemp score and means of staple length and fibre diameter in the whole fleece.The heaviest greasy fleeces were produced by ¾ followed by ⅝ M. Total average greasy fleece weight of the crosses was 3·43 kg. There was a general trend of increase in greasy fleece weight with increasing Merino proportion.The total average percentage clean yield of the crosses was 42·2, and ½ M and ¾ M produced the heaviest clean fleeces. The total average clean fleece weight of the crosses was 1·44 kg. Skirting the fleeces caused a reduction in the within-fleece variability of staple length and diameter. Percentages reduction for staple length were 10·3, 9·6 and 14·6 and those for fibre diameter were 2·4, 5·0 and 9·5 in Barki, crosses and Merino respectively.Barki had the coarsest diameter and the whole fleece of ¾ M showed the finest mean diameter of the crosses. The within-staple variability in distribution of fibre diameter was high in Barki and throughout the crosses. The average percentage medullated fibres was highest in Barki and decreased throughout the series of crosses. The ¼ M had the highest frequency medullated fibres of the crosses.The longest mean staple in the crosses was produced by ¼ M. The within-fleece variability in staple length was generally low. In the crosses, the variability assumed slightly higher values than those of the parental breeds.Kemp production was mainly contributed from the dorsal line, particularly from the back and hip.As regards some wool and mutton characteristics, ⅝ M might be considered the most suitable cross-bred type.With increasing Merino contribution in the crosses, the mean fibre diameter showed a decreasing trend, but a high within-staple variability was maintained throughout the crosses. Inter se mating, in most of the crosses, produced animals that showed relatively more uniformity between fleeces than either both or one of the crosses. Inter se mating of the different cross-bred types with selection of the desired uniformity in length and diameter would be recommended.

Description: SUMMARYGroups of weaner pigs, and single animals, were observed in a temperature-controlled room isolated from external noise and light for periods of up to 4 weeks. Continuous records were made of motor activity, food intake and water consumption.In the presence of a cycle of 12 h light and 12 h dark at 25 °C groups of pigs were most active in the light and took most of their food towards the end of the light period. Single pigs also tended to be more active in the light, but the rhythms were less marked, and one animal was most active during the dark period.In continuous light, rhythms of activity and ingestion tended to collapse after only a few days, particularly in pigs which were kept by themselves. When the ambient temperature was increased to 35 °C during 12 h light and decreased to 25 °C during 12 h dark, a group of pigs was most active in the dark.

Description: SUMMARYThe effect of three different growth patterns from 15 to 40 kg live weight on the feed utilization of lambs was studied. The treatments were: high (H) ad-libitum feed intake, low (L) restricted feed intake and high-maintenance-high (HMH) ad-libitum feed intake from 15 to 25 kg followed by a 50-day period during which live weight was maintained constant, which in turn was followed by ad-libitum feeding. Animals were individually penned and fed a pelleted lucerne chaff-cereal grain mixture. Intakes of pellets were converted to digestible organic matter (DOM) using the results of in-vitro digestion studies. Two animals were killed at the start of the experiment (15 kg) and the remaining 27 animals (nine in each treatment) were killed at common live weights of 25, 30, 35 and 40 kg.A marked reduction was observed during weight stasis at 25 kg in the amount of DOM required daily by the HMH animals to maintain live weight. Despite marked compensatory growth by the HMH animals which were rehabilitated after the period of weight stasis, DOM intakes were similar in both these HMH animals and a corresponding number of H animals over identical live-weight ranges.Differences between treatments were found in DOM intake per unit live-weight gain (H 〈 HMH 〈 L), empty body-weight gain (H = HMH 〈 L) and carcass weight gain (H 〈 HMH = L) from 15 kg until slaughter. DOM intake was utilized more efficiently for gains of all these components by HMH animals during compensatory growth compared with H animals over the same live-weight ranges.DOM intakes were related to energy gains in the carcass both for all animals in each treatment from 15 kg until slaughter, and for the H and HMH animals which were killed at 30, 35 and 40 kg from 25 kg. Comparisons of these data showed treatment differences in the efficiency of DOM conversion to carcass energy (H 〉 HMH 〉 L) and that DOM was utilized no more efficiently by HMH animals during compensatory growth than by H animals over identical live-weight ranges.It is concluded that the increased efficiency of utilization of DOM for carcass gain during compensatory growth was due to changes in carcass composition during the period of weight stasis.

Description: SUMMARYA selection of the hemicellulose-utilizing rumen bacteria isolated by Henning (1979) were partially characterized. These and a number of other cellulolytic organisms were incubated in vitro with teff (Eragrostis tef) cell walls, and the extent of solubilization and utilization by the bacteria of individual cell wall sugars was determined. Results were compared with the action of the bacteria on isolated xylan and cellulose.The cellulolytic rumen bacteria solubilized more of both cellulosic and hemicellulosic sugars in the cell wall than the non-cellulolytic organisms. Bacteria which were unable to solubilize isolated cellulose could also degrade very little of the cell wall cellulose, and this appeared to limit the amount of cell wall hemicellulose which could be attacked.There was no direct relationship between the extent of degradation of isolated xylan and solubilization of cell wall hemicellulose, but those xylanolytic organisms which produced freely diffusible enzymes (as evidenced by production of clearings in 3 % xylan-agar) were more effective in attacking the cell wall than those which did not.Examination of thin sections in the electron microscope showed no relationship between attachment of bacteria to the cell walls and ability to degrade them.

Description: SUMMARYThe fertility of a stock of red deer kept under farming conditions on hill land over a period of 7 years has been assessed. The stock consisted of five cohorts of hinds born in successive years from 1971 to 1975. The fertility of hinds was related to their body weight by the general relationship P = 1 – exp(– 0·085(W– 52)) where Pis the probability that a hind will calve and W is her weight in kg at the time of the rut. When body weight was taken into account in this way, age had no effect on hind fertility. Fertility was, however, poor in one year following a rut which occurred in bad weather. Separation of calves from hinds at the time of the rut had no effect on fertility, and under the farm conditions there was no increase in fertility of hinds which had been barren the previous year above that expected from their body weight. Date of calving was slightly skewed, but 63 % of all calves were born in the first 20 days of June. Smaller hinds calved later; 1 kg body weight increased date of calving by about 0·3 days. Evidence of stag infertility was obtained and it was shown that one stag could effectively mate with 28 hinds such that they mostly calved within a 20-day period. It was possible to run 60 hinds with three stags and obtain calving rates which were similar to those for the hind population as a whole. There were no differences in fertility between matched groups of hinds exposed to one or two stags. The results are compared with those obtained by observation of wild stocks in Scotland.

Description: Previous studies have indicated that improved artificial drainage increases yields of winter wheat by as much as 1 t/ha (Armstrong 1978), and suggested that an important component of this improved yield was the more effective utilization of nitrogenous fertilizer. Further data to support this hypothesis are here presented from the longterm drainage economics experiment at the Drayton Experimental Husbandry Farm, Warwickshire, England (Trafford & Oliphant, 1977; Bee, Dennis & Marks, 1978; Armstrong, 1978). The soil of this site is a non-calcareous pelo-stagnogley of the Denchworth series, and the mean annual rainfall is 617 mm. Both the soil and the climate are typical of much of the English midlands. The results presented here are, however, restricted to a single site, and are consequently tentative.

Description: SummaryTotal, dithionite-extractable (‘free’) and oxalate-extractable (amorphous) Fe as Fe2O3 forms were determined in eight Nigerian soil profiles selected to include four major parent materials and different drainage conditions.Total Fe ranged from 1·98 to 15·01 % Fe2O3, the average contents being 4·40, 8·62, 12·59 and 13·49 Fe2O3 for soils derived from the coastal plain sands, basement complex rocks, shale and basalt, respectively. ‘Free’ Fe ranged from 0·08 to 12·28% Fe2O3, the basaltic soils having the highest content, and those on shale the least. Generally the poorly drained soils had low contents, the free Fe oxide constituting about 61 % of total Fe in well-drained soils, and only about 9% in poorly drained soils.The oxalate-extractable or non-crystalline Fe oxide ranged from 0·04 to 1·21% Fe2O3. The proportion of amorphous iron oxide, indicated by the ‘active’ ratio ‘oxalate-Fe/DCB-Fe’, was higher in poorly drained than in well-drained soils.The clay/DBC-Fe ratio remained constant in the well-drained soils but increased with depth in the poorly drained profiles, indicating a co-migration of free Fe oxide and clay in the former but not in the latter soils.In general, the relative distribution of the different Fe forms appeared influenced by both the parent materials and the drainage of the soils.

Description: SummaryData from experimental and observational studies, in agriculture as in many other contexts, are often unbalanced in respect of important classifications. Treatments may be unequally replicated, some combinations of factors may be omitted, animals may die for reasons unconnected with an experiment. Unless means are adjusted in some manner that eliminates disturbance from unequal representation of different categories, comparisons between treatments may be thoroughly misleading. Optimal procedures for the simpler situations have been familiar to statisticians for a long time. They have been little used by other scientists analysing their own data, in part because of the computational labour and in part because their nature has not been properly understood.Modern computing power removes all excuse for the retention of methods that may be actively misleading because they bias summaries of data, or that are at best inefficient in their failure to estimate comparisons as precisely as is possible. The only remaining barrier is the mistaken belief that good methods are either so complicated that they can be comprehended only by professional statisticians or so devious that truth is destroyed rather than exhibited. This paper attempts to show good methods as inherently rational, to explain their main properties, and to illustrate them on examples small enough for the processes to be clear. The paper neither expounds statistical theory nor instructs in computing practice.

Description: SummaryA closed-circuit respiration chamber was used to study (a) the effect of confinement in a chamber on the heat production of pigs already accustomed to restraint in a metabolism cage; (b) changes in daily heat production of pigs following a reduction in the energy intake; and (c) the effect of increasing or decreasing the environmental temperature.An automatically recharged version of the oxygen burette used by Waring & Brown (1965) is described. During tests of the chamber and burette system the mean recoveries of carbon dioxide and oxygen were, respectively, 0·994 and 0·995.It is concluded that measurements of heat production on the first day of confinement were within the normal range of variation and provided valid estimates of energy expenditure.The minimum value for the respiratory quotient (RQ) occurred on the third day following a reduction in energy intake, and it is concluded that the direct effect of previously ingested nutrients was eliminated by the third day. However, there appeared to be a further decline in heat production until 6–7 days following the reduction in energy intake.The heat production of singly caged pigs fed almost to appetite was similar at 22 and 29 °C. Heat production increased at 15 °C, indicating that this was below the lower critical temperature of fed 25 kg pigs. The response of heat production to the low temperature continued for at least 18 days. Variations in heat production between animals and litters were as high as 15% in three experiments.

Description: SummaryYields of two spring barley varieties, Golden Promise and Maris Mink, were greater at the Scottish Plant Breeding Station (SPBS) than at the Plant Breeding Institute (PBI) in both 1976 and 1977. In both seasons more ears per plant were produced and the number of grains per ear was greater at the SPBS. Weight per grain was greater at the Scottish Plant Breeding Station in both 1976 and 1977, but the distribution of grain size along the ears differed between seasons. Grain at the tip of the ears of plants grown at SPBS in 1976 was lighter than the corresponding grain on the Cambridge-grown plants. In 1977 the SPBS-grown plants had heavier grains at all the main shoot spikelet positions. At the SPBS the relative difference between main shoot and tillers 1 and 2 was smaller than at the PBI.These results are taken to indicate that the combination of climatic factors in Scotland affects plant development in such a way that intraplant competition is reduced and more spikelet primordia survive to form grains and more tillers produce fertile ears.

Description: SummaryAn analysis of development of Golden Promise and Maris Mink spring barley grown in England and in Scotland was made in 1976 and 1977. In both seasons the differences between varieties at a site were small. Rates of leaf emergence and primordium production and the number of primordia formed and the number which died were almost the same at both sites in 1976. In 1977 both leaf emergence and ear initiation started later in Scotland and the rates of leaf emergence and spikelet initiation were slower. Fewer spikelet primordia were formed in Scotland than in England in 1977 but a higher proportion survived to produce potentially fertile florets. Tillers emerged at the same leaf stage of the main shoot and the frequency of tillering differed at some tiller positions between England and Scotland, but the number of tillers produced was similar at both sites.These results show that in Scotland the effect of longer photoperiod which enhances the rate of leaf emergence and primordium production compensates for the lower temperature which slows down these processes. The lower temperature in Scotland particularly in 1977 during the period of spikelet primordium death increased the proportion of spikelets that survived.

Description: SummaryA pot culture experiment with 30 Old Alluvium soils was conducted to evaluate the critical Zn concentration in soils and wheat plants for predicting the response to Zn application. The DTPA-extractable Zn (available Zn) in these soils ranged from 0·37 to 4·50 mg/kg soil, and total Zn in the wheat plants of the control pots ranged from 17 to 65 mg/kg wheat shoots. The DTPA-extractable Zn was found to be positively correlated with organic carbon (r = 0·72, P 〈 0·01), negatively with pH (r = –0·48, P 〈 0·01) and positively with wheat tissue Zn concentration (r = 0·98, P 〈 0·01). The Bray's ‘per cent’ yield value was positively correlated with ‘available’ Zn (r = 0·82, P 〈 0·01) and plant tissue Zn (r = 0·85, P 〈 0·01). The critical concentration of Zn in soil and plant below which responses to applied Zn may be expected was 0·65 mg Zn/kg soil and 24·5 mg Zn/kg wheat shoots respectively. All the soils below 0·65 mg Zn/kg soil responded to Zn application where the ‘per cent’ response at 5mg added Zn/kg soil ranged from 22·65 to 100·00 with a mean value of 58·24 whereas at 10 mg added Zn/kg soil, it ranged from 13·08 to 97·14 with a mean value of 40·08. Soils above the critical limit negatively responded to Zn application.

Description: SummarySeven non-pregnant Murrah buffalo heifers aged 20–34 months and weighing 170–260 kg were used in a 7 × 4 incomplete latin square design to study the effect of feeding mixed diets on voluntary intake over a period of 84 days. Voluntary intake and rate of passage were determined during the last 10 days and digestibility of feed nutrients during the last 6 days of each 21-day experimental period.Maize stover, dry grass and wheat straw were fed ad libitum mixed with either a fixed quantity of berseem hay (MH, GH and WH rations, respectively) or concentrates (MC, GC and WC rations, respectively) to total co. 0·80% of body weight (BW). Berseem hay fed free choice mixed with limited (0·70% BW) concentrates (HC ration) comprised another treatment. The mean daily total dry-matter intake (DMI g/kgW0·75) and total digestible nutrient intake (given in parenthesis) by animals were 62·2 (1·94), 72·2 (2·20), 74·3 (2·30), 75·2 (2·94), 79·5 (2·59), 85·9 (2·78) and 88·5 (2·98), respectively on MH, GH, WH, HC, MC, WC and GC rations. The digestible crude protein intake on the HC ration was higher than on the remaining six rations. Feeding a fixed quantity of either berseem hay or concentrates resulted in lower consumption of basal roughages suggesting that the physical capacity of the gut limited intake.Dry-matter digestibility (%) and mean retention time (h), given in parenthesis, were 57·6 (69·4), 56·3 (64·6), 56·7 (67·5), 72·2 (79·9), 59·2 (620), 59·4 (620) and 58·9 (66·0), respectively on MH, GH, WH, HC, MC, GC and WC rations. The digestibilities of D.M. and proximate principles, except crude fibre (CF), of the HC ration were higher than those of the remaining six mixed diets. Concentrate feeding tended to hasten the movement of digesta of the roughage portion of the mixed diet through the digestive tract. The longest mean retention and rumen retention times were associated with the highest digestibilities. The wheat straw-berseem hay mixed diet was as good as dry grass or maize stover-berseem hay mixed diets with regard to its nutrient intake and weight gain by the heifers.

Description: SummaryThe use of growth resources is examined in an intercropping combination of early sorghum (82 days) and later-maturing pigeonpea (173 days) in a row arrangement of 2 sorghum: 1 pigeonpea.Prior to sorghum harvest, light interception by the intercrop combination was almost as high as sole sorghum. After sorghum harvest, light interception by the remaining pigeonpea was very poor and it is suggested that pigeonpea yield could be increased with higher plant population density and better plant distribution. Soil water measurements indicated that this would increase the amount of water being transpired through the crop but would not increase the total evapotranspiration demand. Higher nutrient concentrations in the intercrop pigeonpea compared with sole pigeonpea during this post-sorghum period suggested that yield of intercrop pigeonpea was not limited by nutrient stress, though the total uptake of nutrients by both crops was much greater from intercropping than sole cropping.

Description: SummaryThe variation in hardening responses under different temperature regimes for three cultivars of Lolium perenne L. is described. The relative cold hardiness of the cultivars was modified by different temperatures during hardening. A threshold temperature existed above which hardening did not occur, but this temperature varied between cultivars.Although continuous low temperatures (2 °C) favoured hardening, hardening also occurred under warm day and cool night conditions (15:2 °C) where cultivars showed contrasting hardiness responses in daylengths of 16, 12 and 8 h. Under some of these conditions both leaf growth and hardiness were possible.The significance of these results is discussed in terms of the development of screening techniques and breeding objectives.

Description: SummaryBody measurements and weights of animals of varying ages were recorded in White Fulani (Bunaji), Sokoto Gudali and N'dama breeds of cattle. Chest girth accounted for 86–96% of the variation in body weight in the three breeds. The linear regression coefficient of weight on chest girth in the N'dama differed significantly from the other two breeds. Within each breed, the regression coefficient of young animals was lower than those of older groups. The variables that contributed most to improving the prediction of weights when added to chest girth were rump length and body length. Animals with low body condition scores had lower regression coefficients of weight on chest girth than those with high scores.

Description: SummaryDifferences in the field emergence of seed lots of vining peas were shown to be largely due to differences in the sensitivity of seeds to imbibition damage caused by the rapid uptake of water. The reduced emergence seen for all lots in wet soil resulted from a faster rate of water uptake and a consequent increase in imbibition damage. This caused both physiological death of low vigour seed lots and enhanced predisposition to pre-emergence mortality in unsterilized soil in all lots. The potential for the chemical protection of seeds against rapid water uptake is discussed.

Description: The efficiency of digestion and absorption is dependent upon the rate at which digesta moves through the gastrointestinal tract. The following report describes the gastrointestinal transit for digesta markers given to ten species of mammals fed the same diet.

Description: SUMMARYEight Morino lambs equipped with simple cannulac in the duodenum and terminal ileum were divided into two equal groups and used to study the net absorption of calcium, phosphorus and magnesium from concentrate diets supplemented by soyabean meal or by ensiled poultry litter. Mean net absorption of Ca, P and Mg for the soya-bean meal and poultry-litter treatments, respectively, was 31·6, 10·1; 34·7, 35·4; and 51·5, 41·6.Irrespective of the diet, the small intestino was the major site for Ca and P absorption and the stomachs for the absorption of Mg. A large secretion of P in the stomachs was found with both diets; 8·50 and 9·32 g/day for the soya-bean meal and poultry-litter treatments, respectively.The results of the present study support the view that poultry litter is a good source of P and Mg for sheep and can be used with deficient diets. Owing to the low rate of Ca absorption from the poultry-litter diet, it appears that at limited levels of inclusion, the extra added Ca would not be a detrimental factor.

Description: SUMMARYThin-layer chromatography and infra-red spectrosoopy were used to identify the components of technical Thanite. A method is developed for qualitative and quantitative determination using a gas liquid chromatograph (GLC) equipped with a flame ionization detector. Two major peaks, having retention times 1 and 5 min, were obtained. This was achieved using a glass column (15 × 0·3 cm), packed with diethylene glycol (1·5%) on chromosorb W, 60–80 mesh, at temperature range 70–170 °C. The results obtained by GLC showed that 33·7–55·8%, and 36·6–68·3% of the initial deposit of Thanite on cotton leaves degraded within 12 h from exposure to sunlight and ultraviolet irradiation respectively. One fifth of the initial deposit of Thanite on cotton leaves was lost after 24 h from spraying, then 70 % of the compound was dissipated after 3 days. Incubation of Thanite with rumen liquor at 39 °C for 24 h under anaerobic conditions resulted in degradation of 45–74% of the initial concentration.

Description: SUMMARYThe influence of various nitrogen and phosphorus sources, applied at the preseeding stage with two placement methods, on maize yield and fertilizer utilization, was studied in two field experiments and a pot experiment with a calcareous, heavy to medium heavy textured recent alluvial soil.Phosphorus alone had no effect on crop yield. Nitrogen alone or nitrogen (various forms) and phosphorus had a clear positive effect on crop yield. As to the various sources the observed differences in the crop yield of the field experiments were not significant, while in the pot experiment ammonium sulphate gave the highest yields.The data on the phosphate concentrations in the tops derived from phosphate fertilizer (Pf) indicate that the presence of nitrogen increased the utilization of phosphorus fertilizer. From the tested placement methods the incorporation method appears clearly superior in the pot experiment with a similar trend in the field experiment for all sources except ammonium phosphate-sulphate.The utilization coefficients of the nitrogen fertilizer sources suggest that ammonium and urea were better utilized than nitrates, that the higher nitrogen utilization reflected higher yields and that phosphorus fertilizer exerted a beneficial effect on nitrogen fertilizer utilization. Finally they suggest that the addition of 120 kg N/ha enhanced the amount of soil nitrogen taken up in the maize grain by 53%.

Description: Singh & Taneja (1978a, 6, 1981) have reported on several aspects of salinity tolerance in Indian desert sheep breeds, for example, maintenance of body weight, feed and water intake, body water compartments and blood characteristics. No report is available in the literature on the effect of varying levels of salt intake from drinking water on reproductive performance in these animals. The earlier reports on salinity tolerance in sheep have been almost wholly based on the animals' response to different levels of sodium chloride in synthesized drinking waters. It is, however, generally agreed that the upper limit of total salt tolerance in sheep depends not only on the concentration of the most abundant salt constituent in the drinking water (usually sodium chloride), but also on the concentrations of the other constituents. Divalent cations (calcium and magnesium) and anions (sulphates and carbonates) in the water are believed to be more toxic than the monovalent cations and anions (sodium and chloride).

Description: SUMMARYThe effects of N, P, K and Na silicate fertilizers, and drought on the concentrations of K in the dry matter and tissue water of field-grown spring barley crops have been investigated. Percentage K in dry matter depended on the amounts of N, P, K or water received by the crops and was linearly related to fresh weight to dry weight ratio, but the slope of this relationship depended on whether or not the crops received K. Expressing K concentrations on the basis of tissue water eliminated differences between crops, except for those given insufficient K. Barley crops given fertilizer K maintained K concentrations in their tissue water of about 200 mmol/kg tissue water for most of the growth period but crops grown without K had only 50–70 mmol/kg tissue water. The results indicate that K concentrations in the tissue water are a more reliable indicator of tissue K status than % K in dry matter.Decreases in crop K content resulting from poor K supply were balanced by increases in Na and Ca (but not Mg) contents so that total cation concentrations in the tissue water were similar in low and high K crops. The extra Na and Ca are probably primarily involved in maintaining charge balance for anion absorption but once in the plant they may also substitute for K in its osmotic role.

Description: The main source of skin surface protein is sweat glands. Studies on skin surface proteins of domestic animals have been made by Joshi etal. (1968), Jenkinson, Lloyd & Mabon (1976, 1979), Lloyd, Mabon & Jenkinson (1977) and Rai, More & Singh (1982). However, information on sweat proteins (skin surface proteins) of goats is lacking. The present study is an effort to characterize sweat proteins of goats and to compare them with those of sheep.

Description: Vascular injection or infusion of isotopically labelled fatty acids into both ruminant and nonruminant species has been used as a method for determining the entry rate of non-esterified fatty acids (NEFA) into blood (Bickerstaffe, Annison & Linzell, 1974; Vranic, 1975). Results obtained in this way represent the release of fatty acids from several sources, principally adipose tissue. The predominant labelled end-products from [3H]– and [14C]fatty acid metabolism are water and carbon dioxide respectively. Both these metabolites enter extensive body pools and the label is unlikely to be reincorporated into plasma NEFA during the time course of conventional short-term experiments (2–4 h). During isotope dilution experiments, however, some labelled fatty acid could be incorporated into adipose tissue triacyglycerol (TAG) following synthesis of low-density lipoprotein in the liver. In addition, the contribution of NEFA carbon to endogenous acetate production could result in transfer of 14C in any C, or 8H attached to the C8 position in acetate, from the infused fatty acid to fatty acids synthesized by liver and adipose tissue.

Description: SUMMARYSeveral nitrification inhibitors were compared with nitrapyrin, which was taken as the standard, when injected with aqueous urea into ryegrass leys at Rothamsted during 1977–81 and at Liscombe Experimental Husbandry Farm, Dulverton, Somerset, during 1977–9. Injection was done in either autumn or winter or spring.All the inhibitors slowed down the rate of nitrate formation from the injected urea. Sodium trithioearbonate (STC) was less effective than nitrapyrin and potassium ethyl xanthate (KEtX) less effective than STC. A mixture of nitrapyrin and carbon disulphide was better than nitrapyrin alone, and a mixture of STO and KEtX was better than STC alone.At Rothamsted, injecting inhibitors in autumn or winter improved yields and N uptakes, probably because they prevented loss of nitrate N by leaching and perhaps by denitrification. STC, STC-KEtX mixture and etridiazole were as good as, and nitrapyrin–CS2 mixture better than, nitrapyrin alone. Injecting inhibitors in spring frequently decreased yields, perhaps because NH4:NO3 ratios were too large, and increased them only when more than 150 mm of rain fell afterwards.At Liscombe, where rainfall was higher, but soil temperatures were similar to those at Rothamsted, the benefits from using inhibitors in autumn were larger, but there were none from using them in spring.

Description: SUMMARYIn the application of the Scholander pressure chamber technique to cassava water relations studies, the leaf water potential measured on central lobules was initially compared with that measured on entire leaves (including petiole). Measurements made using both a Campbell-Brewster hydraulic press and a pressure chamber of the leaf water potential in six different cassava clones were also compared. Although the central lobules showed a greater sensitivity to moisture loss after sampling than entire leaves, their leaf water potential was in close agreement with those measured on the entire leaves (r3 = 0·96). Therefore, for routine and field estimates in cassava, measurements made on the central lobules may be used to avoid the large reduction in total leaf area. The Campbell-Brewster hydraulic press satisfactorily estimated leaf water potential in M.Col. 1684 clone, which had the longest and narrowest lobules, but in other clones the leaf water potential was overestimated at high leaf potential (〉 -12·5) and underestimated at low water potentials (〈 -12·5). Over a wide range of leaf water potentials, a poor relationship between leaf water potentials estimated with hydraulic press and with the pressure chamber was observed for cassava because press estimates are influenced by lobule length and lobule width.

Description: SUMMARYOne hundred and eighty triple test cross families arising from three barley crosses (C 164 x EB 1556, BG 25 x NP 21 and BH 15 x RD 103) were grown in two blocks of a randomized-block design in saline-alkali soil prepared in micro-plots. The families were evaluated for number of days from sowing to heading, plant height, number of tillers per plant, ear length, number of grains per ear, 100-grain weight and grain yield per plant. The cross BG 25 x NP 21 showed epistasis only for number of days toheading and number of grains per ear; in contrast, epistasis was present in all traits in BH 15 x RD 103. In cross C 164 x EB 1556, epistasis was detected for plant height, ear length and number of grains per ear. Thus, epistasis appears to be related to specific cross combination. The ‘j and l’ type epistasis was more pronounced than the ‘i’ type. Early generation selection may be used for number of days to heading which Exhibited epistasis marginally with preponderance of additive gene effects, while for the remaining traits selection should be deferred till an advanced generation.

Description: SUMMARYGeneralized lattice designs (a member of the class of incomplete block designs) have been used in 13 potato variety yield trials over 3 years. Results from these designs are shown to be generally more precise than from comparable complete block designs.

Description: SUMMARYWool follicles and fibres of pre-ruminant lambs abomasally fed isoenergetic diets with daily amounts of lysine ranging from 0·12 to 1·94 g/(kg live weight)0·75 were examined by light and electron microscopy. In lambs which received ca. 0·9 g lysine/kg 0·76 daily, the follicles appeared normal, whereas in those which received less than 0·9 g lysine/kg0·75 daily several follicle abnormalities developed and the percentages of follicles affected increased as the amount of lysine was decreased. These abnormalities included the formation of autophagic vacuoles (or apoptotic bodies) in follicle bulb cells, and retarded and incomplete keratinization of the wool fibres, which led to the kinking of fibres at the mid-dermal level and gross distortion and partial degradation of fibres in the distal parts of follicles with thickened outer root sheaths. Following the introduction of a low-lysine diet, autophagic vacuoles developed in most follicle bulbs within 24 h. Impaired keratinization and kinking of fibres were evident in increasing proportions of follicles after 2 days, and gross distortion of fibres after 3–4 days. When the lambs were returned to a diet with adequate lysine recovery of normal follicle structure followed a similar time pattern, except that gross distortion of fibres persisted in the distal parts of some follicles for longer than 1 week. In some lambs given more than 0·9 g lysine/kg0·75 daily a small percentage of follicles had short keratogenous zones. Clumping of fibres, which occurred in the proximal parts of a small number of follicles, was unrelated to the amount of lysine in the diet.

Description: SUMMARYResults are presented from two experiments (1973 and 1974) in which high potato yields were obtained (60–70 t/ha). In both, Désirée and Maris Piper accumulated much more N and K (〉 200 and 300 kg/ha respectively) than was applied as fertilizer (160 kg N and 189 kg K/ha). Increasing planting density (to levels above commercial practice) increased nutrient accumulation but had only small effects on yields. Thus, high yields are associated with but not necessarily caused by large accumulations of nutrients. As a general principle, increasing fertilizer rates above those shown to be optimal will not increase yields.

Description: The objective of this study was to examine the effect of the chemical growth regulator Terpal (a mixture of mepiquat chloride and ethephon or 2 chloroethyl phosphonic acid) on the pattern of branching, plant height and yield components of winter oil-seed rape (cv. Jet Neuf). Mepiquat chloride (a quaternary ammonium compound with similar antigibberellin properties to cycocel) was developed as a morphoregulator for cotton where it has been shown to reduce plant height, shorten internodes and increase boll retention (Willard et al. 1977). The activity of ethephon has been attributed to its release of ethylene which influences a wide range of developmental processes, for example fruit abscission and ripening (Chatterjee, 1977; Gvozdenovic, Dulic & Slavic, 1978), growth retardation (Van Andel & Verkerke, 1978) and also the extent of lodging in cereals (Hill, Joice & Squires, 1982).

Description: Early investigations into the effects of the growth retardant chlormequat on wheat and barley showed that in the absence of lodging the number of ears was frequently increased following treatment at the beginning of stem elongation (Humphries, Welbank & Witts, 1965; Alcock, Morgan & Jessop, 1967; Barrett, Meens & Mees, 1967). More recently, earlier applications, at the three-leaf stage, to barley have been shown to be more effective in increasing the number of ears (Koranteng & Matthews, 1982). However, there appears to be little information on the effects on number of ears of early application of chlormequat to winter wheat. Therefore, in 1982 three field experiments were carried out to investigate the effects of early application of chlormequat on the numbers of tillers and ears and grain yield of winter wheat.

Description: SUMMARYSheep were grazed for 2 years at stocking rates of 7, 14, 21 and 28/ha on a pasture comprising Lotononis bainesii and Digitaria decumbens cv. Pangola at Mt Cotton, south–east Queensland. There were six replicates of each treatment grazed in rotation with 3 days' grazing followed by 15 days' rest.The initial dominance of lotononis was lost after 6 months of grazing and lotononis failed to persist satisfactorily at any stocking rate. Demographic studies showed that lotononis behaved as a short-lived plant, predominantly annual, with some vegetative perennation as stolon-rooted units under heavy grazing. Soil seed reserves varied from 5800 to 400 m2 at the lightest and heaviest stocking rates respectively. Lotononis failed to regenerate under Pangola shading or inopportune high grazing pressure. Soil bulk density (0–7 cm) increased from 1·2 to 1·4 g/cm3 according to stocking rate.

Description: SUMMARYLeft and right 9–10–11 rib joints from 104 Madura, Ongole, Bali, Grati (or Friesian cross) and buffalo bulls were dissected into bone, muscular and fatty tissues and then ground and chemically analysed for water, ash, ether extract and protein contents. The carcasses from 48 of these bulls were also ground and analysed for these same chemical components. Within-breed relationships between dissectible and chemical composition in the rib and between dissectible composition of the rib and chemical composition of the carcass were tested by regression analyses.There were no breed differences in the relationships between bone and ash or between muscle and protein in the rib, but at the same content of rib fatty tissue, buffaloes had less predicted rib ether extract than Bali, Ongole or Madura cattle. At the same ash content of the rib, Madura bulls had the most carcass ash. Rib-muscle content was considered to be a poor predictor of carcass protein. At the same fat content of the rib, breed differences in predicted carcass ether extract were large with Grati having higher levels than Bali and all four cattle breeds having higher levels than buffaloes. Use of rib-fat or rib-energy contents to predict carcass energy yielded relative breed differences similar to those when rib fat was used to predict carcass ether extract.Differences in the distribution of fat within the carcass, particularly in the subcutaneous fat depot, were considered to have a major bearing on differences in the within-breed relationships. Therefore, published part-whole prediction equations should be used with caution when comparing genotypes likely to differ in the distribution of tissue within the carcass.

Description: SUMMARYThe effects of some plant growth regulators on the growth and development of two cultivars of oil-seed sunflower (cvs Flambeau and Luciole) were examined in 1977 and 1978. Sunflower is a marginal crop for the United Kingdom, being late maturing and susceptible to infection by grey mould (Botrytis cinerea) during the seed-filling period.An experiment in 1977 indicated that suitable growth regulators might improve sunflower husbandry principally by shortening the stem, allowing late applications of fungicide and insuring against lodging. A mixture of mepiquat chloride and ethephon (BAS 098 OOW) was the most effective stem shortener. Daminozide gave variable effects on yield depending on the rate and time of treatment. The number of seeds per m2 was the major determinant of yield; 1000-seed weights and oil contents were similar for all treatments. The proportion of linoleic acid in the oil was very high in all experiments.In 1978 a second experiment involving daminozide and two sunflower cultivars revealed seasonal and varietal differences in response. The timing of growth regulator application seemed critical to affect seed yield. The third experiment, in 1978, investigated the results of applying BAS 098 OOW to four plant population densities varying from 40000 plants/ha to 160000 plants/ha. High plant population density advanced maturation by 2 weeks, but in these plots the crop lodged in the absence of growth regulator treatment.

Description: SUMMARYThe residual effects of sulphur-coated urea (SCU) fertilizers were evaluated by measuring the pH and mineral-N in the soil profile after 2 years of application of these fertilizers to soils in the various ecological zones of the savannah of Nigeria. Changes of 0·2–0·3 pH units relative to the control (without applied N) were detected on the sandier soils at Kadawa and Mokwa but not on the heavier Samaru soils. There was little or no difference among the sulphur-coated urea and calcium ammonium nitrate in their acidification effects. Also residual nitrogen levels were low in plots that received SCU but did not differ significantly from those of calcium ammonium nitrate.

Description: SUMMARYTwo sources of sulphur-coated urea (SCU) were compared with calcium ammonium nitrate (CAN) as sources of N for cotton and sorghum in the savannah zone of Nigeria. At the lowest rate of N application (30 kg/ha for cotton and 40 kg/ha for sorghum), SCU-11 with a dissolution rate of 11% in 7 days was found to be more effective than SCU-30 having a dissolution rate of 30% in 7 days and CAN. A single application of SCU-11 produced a higher sorghum yield than a divided application of CAN at the same rate. These results indicate that a slow-release nitrogen fertilizer might be useful for improved grain sorghum and cotton varieties.

Description: SUMMARYHypocuprosis has been diagnosed for 4 years in calves of a beef suckler herd at Warren Farm, Berkshire. The copper (Cu) contents and distribution in the soil at that site, as well as changes in herbage Cu throughout the 1979 grazing season, were examined. The herbage Cu concentration was always less than 7·5 μg/g and decreased markedly to 3·0 μg/g during July. Serum Cu contents of both untreated cows and untreated calves also decreased markedly, but at a much earlier stage than the decrease in herbage concentration. One untreated calf developed severe anaemia, but recovered when treated with Cu Ca EDTA. Although changes in the coefficient of absorption of dietary Cu were caused by changes in S and Mo contents, the calculated availability of Cu was dominated by the Cu content per se. Thus the calculated availability remained relatively high during the period when serum concentration decreased.The decrease in serum Cu may have occurred as the result of a differing availability of Cu in ensiled and grazed herbages. However, coincident with the decrease in serum Cu was a high concentration of Fe in the grazed herbage which was largely associated with the surfaces of the leaves. It is therefore possible that the development of Cu deficiency immediately after the animals started to graze was precipitated either through an interaction between Cu and Fe in the animal, or because of a reduced availability of Cu through an interaction with ingested soil.

Description: SUMMARYCattle grazing buffel grass pastures during the dry season at Katherine lose large amounts of live weight during a short period following first rain. In Part 1 we showed that these losses were due mainly to reduction in gut contents. Part 2 examines the changes in pasture, diet and grazing behaviour to assess the probable change in nutritional status of cattle following rain.During the dry season the most valuable pasture component, green leaf, was very scarce and had a nitrogen concentration of about 1%. Diets of oesophageally-fistulated cattle contained less than 0·5% N. Shortly after first rain diet N doubled owing both to rapidly increasing amounts of green leaf and to the increase in N concentration in young leaf to over 3%. Although intake was not measured, literature is cited to show that this increase in dietary N would be expected to increase rumen digestion rates with a resultant marked increase in D.M. intake and a reduction in gut contents.Although availability of high quality herbage increased very rapidly following first rain, a period of increased nutritional stress immediately following rain could not be ruled out. However, any such decline in nutrition appears to be short-lived.

Description: SUMMARYFive selections of Stylosanthes guianensis var. guianensis with a short-day flowering response were grown at three sites at altitudes of 10, 280 and 1000 m on the island of Bali, Indonesia at latitude ca. 8° 30′ S. Mean site temperature was ca. 6 °C lower at the highest site whilst mean short-wave radiation was lowest at the intermediate site.Date of 50% floral initiation (FI) varied from 1 February to 21 June, when daylength (sunrise to sunset plus half civil twilight) decreased from 12·85 to 12·00 h. FI was independent of site for cv. Graham and cv. Cook, but at 1000 m it was 14 and 77 days earlier for cv. Endeavour and cv. Schofield respectively relative to the 280 m site. Little flowering of cv. Schofield occurred at 10 m, and it is suggested that cool temperatures promoted an increase in the critical photoperiod for this cultivar, or that warm temperatures inhibited flowering. FI was delayed at 1000 m in CPI 34906.The duration of the phase from FI to flower appearance (FA) varied from 29 to 75 days according to selection and to site, and was negatively related to mean temperature, radiation, and maximum temperature for cv. Graham, cv. Cook, and CPI 34906 (but not for cv. Endeavour). Number of nodes at FA in this determinate species generally reflected growing conditions in the pre-flowering phase and was positively associated with age at FA in plants of particular varieties.

Description: SUMMARYExperiments are described which study the effect of density and chop length on the rate of diffusion of oxygen into silage and equations are presented which enable the rate of diffusion to be calculated under laboratory conditions. The concept of zero porosity is also discussed and methods of calculating the density at which it occurs are given. The effect of carbon dioxide on the rate of diffusion is also discussed.

Description: SUMMARYIn Expt 1, four groups of seven hypocupraemic ewes were repleted with a semipurified diet containing 7·2 mg Cu, 3·5 gS and 0·5, 2·5, 4·5 or 8·5 mg Mo/kg D.M. as ammonium molybdate for 65 days. The first increment in Mo caused the largest reduction in plasma Cu repletion and the second completely inhibited repletion but the final increment led to a partial recovery. The highest Mo level caused marked increases in plasma Mo and reduced rumen sulphide concentrations.In Expt 2, five groups of four hypocupraemic ewes were repleted with hays containing 7–8 mg Cu, 3–3·4 g S and 0·4, 2·8, 4·3, 14·2 or 18·7 mg Mo/kg D.M. for 21 days. The hays were made in June from pasture sprayed earlier with 0–800 g Mo/ha as sodium molybdate. Qualitatively the changes in plasma Cu distribution and Mo content showed the same curvature with increases in dietary Mo as those in Expt 1.In Expt 3, four groups of five hypocupraemic ewes were repleted on pastures which had received a spring foliar dressing of 0–800 g Mo/ha. Herbage in the four plots was grazed in July, when it contained 0·7, 3·5, 5·9 or 12·4 mg Mo, 6'4 mg Cu and 2·7 g S/kg D.M. and again in September. Quadratic responses to Mo were demonstrated on both occasions, but, for a given Mo level, responses in caeruloplasmin synthesis were much lower than in Expt 2.It is concluded that Cu absorption is inhibited most by 4–6 mg Mo/kg D.M. and that inhibition of S2- production at higher Mo levels may give rise to a recovery in Cu absorption. Semi-purified diets give responses which lie roughly between those for fresh herbage and hay.

Description: SUMMARYThe incidence of lamb mortality from birth to 8 months of age has been studied over a 6-year period in an upland, grassland flock of sheep comprising the Scottish Blackface, Cheviot and Welsh Mountain breeds and the crosses among these breeds. Each breed and cross-bred type was maintained at varying levels of inbreeding. Approximately half the lambs which died were stillborn or dead on the day of birth, nearly 40% died thereafter but before weaning and about 10% after weaning.Post-mortem examinations on 586 of the 632 lambs which died from among the 2453 born attributed death on average to two causes per lamb. Approximately 11% of the causes were stillbirths or delayed births; 11% were cases of dystokia; congenital defects of various types accounted for about 10% of the causes; 25% made reference to weakly lamb, exposure or starvation; 14% to infectious diseases and 16% to noninfectious diseases. The extent to which causes of death occur together is examined.Breeds differed in mortality rate with the Welsh the lowest and Cheviot the highest. Cross-breds were better than the average of the pure breeds but this advantage emerged only in the period between 3 days and. 6 weeks of age. Inbreeding, both of dam and of lamb, increased mortality. Lambs from dams which were crosses of inbred lines had the best survival. Litter size, type of rearing, parity of dam, sex of lamb and birth weight also had significant effects on mortality rate.

Description: SUMMARYYield variability of spring barley and winter wheat varieties is investigated in National Institute of Agricultural Botany trials sown to assess the influence on varieties of fungicide treatment. The extent of the variation in relative variety performance due to years and centres is estimated for untreated and treated yields and for yield response to fungicide. The consequences for the design of future trials systems are considered.

Description: SUMMARYNitrosoguanidine-induced acid-tolerant mutants S1 and M1 of Lens esculenta Rhizobium leguminosarum were used for nodulation and symbiotic N2-fixation in acid soils having different pH and associated factors of acidity. The range of soil pH and associated acidity factors in which nodulation and N2-fixation responded varied, depending on mutant strains. However, strain M1 was more responsive and effective than S1. Antagonistic effect of Mn to Fe was found when the active Fe2+ and total Mn were determined in fresh nodules.

Description: Controversy exists in the literature concerning the validity of the nylon bag technique for investigating the nutritive value of feeds (Pidgen, Balch & Graham, 1980; Marten, 1981). Avariety of factors have been implicated in affecting results such as sample size, fineness of grinding and positioning of bags in the rumen. In addition basal ration has been shown to affect results (Lindberg, 1981 a, b; Siddons & Paradine, 1981). ørskov & Hovell (1978) showed that rate of digestion of hay in nylon bags was faster when the animals were fed on Pangola (Digitaria decumbena) hay rather than on sugar cane with its high sucrose content. In further work Ganev, ørskov & Smart (1979) reported that vegetable proteins degraded at a faster rate when incubated in nylon bags in sheep receiving dried grass rather than whole barley as their basal ration.

Description: A noticeable feature of mammalian skin surface lipids is the considerable variation in lipid and fatty acid compositions that exists between species (Nicolaides, Fu & Rice, 1968). The sebaceous lipids of oxen are characterized by the presence of relatively high levels of triglycerides, which, in contrast to those of other bovine tissues, contain a significant proportion (〉 20%) of linoleic acid (Noble, Crouchman & Moore, 1974; Smith, Noble & Jenkinson, 1975; O'Kelly, Reich & Mills, 1980). The uniqueness of these highly unsaturated triglycerides has indicated possible roles in the chemical and biological defence systems of the skin surface for linoleic acid released by hydrolysis (Jenkinson, 1980). The skin surface triglycerides of calves do not attain the high levels of linoleic acid displayed by adults until 4–5 weeks after birth (Noble et al. 1975). It is, however, not known if a new-born calf compensates for this difference by an increase in sebum triglyceride concentration and output or, in view of the decreased availability of linoleic acid at this Stage, produces a sebum of widely different composition from the adult.

Description: SUMMARYField studies were carried out to determine the sources of photosynthate for developing pods and to assess the effect of defoliation and flower removal at different stages on the performance of lentil. The leaves of flowering nodes were the primary source of assimilate to pods. Removal of 25–75% of leaves reduced seed yield by varying degrees depending on crop growth stage. The plants compensated for the loss of foliage to some extent, possibly through increased efficiency of the remaining leaves. One complete or 50% defoliation reduced seed yield to different extents at the vegetative, flowering, early pod formation and late pod formation stages, the greatest effect being seen at flowering and early pod formation. Plants compensated considerably by production of new leaves when defoliated at the vegetative phase. Increased moisture supply greatly enhanced the compensation ability of the lentil plants.Removal of all flowers up to 1–2 weeks after an thesis under unirrigated conditions and up to 3 weeks after anthesis in irrigated conditions did not adversely affect the seed yield. Flower removal beyond this period resulted in a significant reduction in seed yield. Little seed yield was obtained when flower removal was continued for either 6 or 8 weeks under unirrigated conditions. The plants compensated for the loss of earlier-formed flowers by setting pods from later-formed flowers. Compensation was greatly enhanced when the crop was irrigated during the reproductive phase. There was relatively little or no effect of the deflowering treatments on the number of seeds per pod or weight per seed. The flowering period of the deflowered plants was extended and their senescence was delayed. When 25% of the flowers were removed at different intervals during the reproductive phase, seed yield was not adversely affected. An increased intensity of flower removal decreased yield but the decrease was not proportional to the degree of flower removal. The plants apparently compensated by setting new pods.

Description: SUMMARYThree adjustment methods using control plots to adjust for soil variation in a modified augmented design (Lin & Poushinsky, 1983) were studied by simulation. The results show that adjustment by design structure (row and column correction factors) is best when soil variation is relatively uniform in one or two directions, while adjustment by regression analysis is best when the variation is multi-directional. Adjustment using the control plot as a fertility index is least satisfactory. A modified augmented design in a replicated experiment is generally inferior to a balanced lattice square design but is competitive when the percentage of environmental variation attributable to soil factors is less than 70% of the total variation.

Description: Pyrethrum is a small bushy perennial crop cultivated for its flowers which have insecticidal properties. Pyrethrins, the active principles in the flowers, are contact insecticides causing nervous breakdown leading to paralysis and death of insects. Kroll (1963) and Parlevliet, Muturi & Brewer (1968) have shown that the flower yields of pyrethrum could be improved by applying P fertilizer whereas N and K fertilizers did not increase the yields. On the other hand, Mwakha (1979a, b) showed that pyrethrum responds to N fertilizer on soils deficient in N. The present investigation was carried out to study the response of pyrethrum to various rates of application of N, P and K and sources of phosphorus.

Description: SUMMARYDiurnal and seasonal changes in the total, osmotic and turgor potentials of winter wheat leaves are compared in two seasons of mild and severe soil water stress. Gradients of total water potential in the soil-plant system are also presented. In both seasons the total water potential of the leaves decreased in parallel with the soil water potential, concurrently leaf osmotic potential also decreased sufficiently to maintain positive leaf turgor potential. Eventually, under severe water stress, soil water potential approached –1·5 MPa and leaf turgor potential tended to zero during the middle of the day.The potential drop across the soil-root system was twice that along the stem. Estimates of the water potential at the root surface varied diurnally and were often lower than the bulk soil water potential. In dry soil plants were unable to equilibrate with the soil water potential overnight. These results are consistent with the existence of significant resistance to water flow across the rhizosphere.

Description: SUMMARYBody heat storage changes of cattle were measured by means of simultaneous direct and indirect calorimetry and by thermometry in an environment that alternated in temperature between 12 and 25 °C. When the calorimeter temperature was increased deep body temperature (Tc) increased by approximately 0–5 °C, mean surface temperature (Ts) by 3 °C and mean body temperature (determined from calorimetry, Tb) by 1 °C, but these increases were not fully sustained during the next 24 h. Changes in the three temperatures were related by the equation: δTb = αδTc+(1-α) δTs where a was found to be 0·89±0·027 (S.E.).

Description: SUMMARYThe modelling of the redistribution of soluble salts in soils, in which it is assumed that the amount of water transferred from layer to layer is related to the excess over field capacity of the water content of a layer, is critically examined.The equation obtained from the dispersion equation by neglecting the diffusive term is solved for the leaching of surface-applied nitrates. It is shown that, by comparing the finite-difference form of this equation to the algebraic formulation of Burns' (1975) model, the two approaches are essentially the same, but that Burns makes approximations that are too inaccurate. In particular, it is incorrect to relate the transfer of water to the excess over the field capacity of the water content of the layer. Burns' model, when applied correctly, requiresmany calculations to be performed, which is costly of computer time. However, it is unnecessary in this problem as the analytic solution is simple and quick to apply.

Description: SUMMARYSpring barley straw treated with NaOH, either chopped and ensiled or ground and pelleted, was compared with long untreated straw and hay, in mixed diets of compound and forage fed to yearling dairy heifers. Protein allowance and source were varied by the inclusion of either fishmeal, soya-bean meal or urea in the diet.Growth rate was improved in two out of three trials by chopped ensiled straw treated with NaOH, compared with long untreated straw, and equalled that supported by hay. Dry-matter intake and digestibility were also improved, although rumen NH3-N concentrations were low. With ground pelleted straw treated with NaOH the effects were less decisive: growth rate was increased once and reduced once compared with long untreated straw, but dry-matter intake was substantially increased. Digestibility remained similar to that of long untreated straw, and was unchanged by rate of feeding. NaOH treatment resulted in small changes in molar proportions of VFA. Digestibility of hay fell when concentrates were added to the diet.Fishmeal increased growth rate with all forms of straw and hay and was more efficient in this respect than either soya-bean meal or urea.

Description: SUMMARYThe mineral content of N, P and K in leaves, stems, roots and seed of field beans, subjected to four watering regimes were compared in 1976 and 1977, and of a foliar nutrient spray in the latter year.N, P and K content increased in all treatments with the increase in plant size and then declined at about the time of podding and death of the leaves.Water shortage reduced the amounts of N, P and K throughout the growth period and for the seed at final harvest; the decrease was more pronounced in 1976 than in 1977. The plants under stress conditions benefited from the foliar nutrient spray more than the unstressed plants.

Description: SUMMARYThe concentration of glutamate and of glutamine was measured in whole blood obtained from a maternal artery, a uterine vein, a foetal artery and an umbilical vein of chronically catherized ewes and foetuses from 100 to 140 days after conception. The activities of glutamate dehydrogenase, phosphate-dependent glutaminase, phosphateindependent glutaminase, glutamine synthetase, γ-glutamyl transferase and glutamine-oxo-acid aminotransferase were measured in placentomes obtained from ewes during a similar period of gestation.The concentrations of glutamate in blood from maternal vessels remained constant, whereas there was a significant decline (P 〈 0·001) in the concentration of glutamate in foetal blood. Glutamine concentrations declined significantly (P 〈 0·05) in maternal blood and in foetal arterial blood (P 〈 0·001), whereas the concentration of glutamine in umbilical venous blood remained constant.Mean arterio-venous differences for glutamate indicated that there was no net uptake from or release into maternal blood by the uterus. However, there was a significant (P 〈 0·02) uptake of glutamate by the placenta from the foetal circulation. Glutamine release from the placenta into the foetal circulation increased as the foetus matured.Significant activities of glutamate dehydrogenase, γ-glutamyl transferase, glutamine synthetase and phosphate-dependent glutaminase were found in the placenta but there was no significant relationship between the activities of these enzymes and the gestational age of the foetus. The enzyme profile indicated that the placenta has a substantial potential for net glutamine synthesis.It is concluded that, for a 140-day foetus, the release of glutamine from the placenta accounts for more than half of its nitrogen requirement. Direct placental transfer of glutamine from maternal blood accounts for only one-third of the glutamine released by the placenta into the foetal circulation of a 140-day foetus. Therefore, the remainder of the glutamine is synthesized in the placenta from glutamate. Only one-third of the glutamate required for this placental glutamine synthesis is from the glutamate released by the foetus. The remainder must be derived either from 2-oxoglutarate, as the result of aminotransferase or glutamate dehydrogenase activities, or from glutathione by the action of γ-glutamyl transferase.

Description: SUMMARYA series of trials were conducted during 1979–82 under semi-arid conditions in a Mediterranean-type environment to study the edge effects in mechanized durum wheat and barley variety trials when uncropped pathways are left between plots. Varietal differences in edge effects on grain yield were in most trials not significant. Thus, edge effects do not distort significantly the relative ranking of varieties.Edge effects were significant for all traits studied and higher in grain and straw yields. These effects were also higher in drier seasons. The overestimation of grain yield from whole plots was 13–18% in relatively high rainfall seasons and 29% in a dry season. In two seasons the scores on the two outer rows were higher than on the two central rows by 89 and 117 % for grain yield, by 72 and 73% for straw yield, by 44 and 48% for numbers of tillers, by 6% for 1000-grain weight and by 14 and 40% for number of grains per tiller. The edge effect was not confined to the outer rows, but it extended to the inner rows of the plot; the magnitude of this effect varied with season and trait.Rows adjacent to the pathway and unprotected from wind had a lower value for all traits than the opposite rows of the pathway, which were protected by the inner rows.

Description: SUMMARYResults are reported from four separate trials carried out to determine the precision of the Sonatest (simple A-mode ultrasonic machine) and the Scanogram (modified linear scanner) for predicting the body composition of live cattle. Cattle in the four trials differed in breed, sex and origin, and the data provided an opportunity to determine the consistency of results in different circumstances. A total of 210 cattle were involved.Fat thickness measurements (Sonatest and Scanogram) and fat and M. longissimus areas (Scanogram only) were taken at the 10th and 13th ribs and at the position of the 3rd lumbar vertebra. Their precision as predictors of carcass tissues percentages was examined when they were used in addition to live weight at evaluation.There was little consistency between trials in the positions and measurements which gave the most precise prediction. The lowest within-breed residual standard deviations of carcass lean percentage obtained with fat thickness measurements taken by Sonatest were in the range 2·5–2·7 and there was little advantage in using additional measurements in multiple regression.Fat areas taken by Scanogram were more precise predictors (within-breed residual standard deviations were close to 2·0). Precision was improved marginally to about 1·8 by using combinations of fat areas but M. longissimus areas were of little additional value.

Description: Differences in the partitioning of fat in the carcass may affect ‘carcass quality’ and depending upon the particular market requirements the optimum partitioning of fat may vary. Differences in fat partitioning may also affect the accuracy with which total carcass fat can be predicted from an assessment of subcutaneous fat (Pomeroy & Williams, 1974).

Description: SUMMARYThe relationship between calcium and phosphorus metabolism in wether sheep given high or low Ca diets, with or without 1α-hydroxycholecalciferol (1α-0H-D3) has been studied by a mineral balance and radioactive technique.Ca absorption was not related to Ca intake but was stimulated by 1α-OH-D3. More Ca was absorbed by treated animals from the high Ca diet than from the low diet and all the extra Ca absorbed was retained, increased retention being brought about largely by an increase in the rate of bone accretion.P absorption was increased to approximately the same extent from both diets suggesting that stimulation was due to the 1 α-0H-D3 treatment rather than increased Ca absorption. Whereas the extra P absorbed from the high Ca diet was retained, together with Ca, in bone and soft tissues, that absorbed from the low Ca diet was largely excreted in the urine. It is suggested that this difference in P retention reflects a difference in availability of Ca for retention in bone and P retention was in fact found to be directly related to Ca retention.The roles of secretion of P into the gut, absorption of P from the gut and urinary excretion of P are discussed in relation to P homoeostasis.As absorption of P from the intestine and loss of P to bone, soft tissues and urine increased, so endogenous faecal loss decreased until it reached a value of approximately 35 mg/day per kg body weight when it remained constant. It is suggested that this value may represent the inevitable loss of endogenous P in the faeces from a hay and concentrates diet and that this minimum value may have a bearing on the calculation of P requirements.

Description: SUMMARYAnimals fed sole diets of kale (Brassica oleracea) were compared with animals fed ryegrass-clover pasture grown on the same soil type in two experiments. In Expt 1 young cattle grazed the two forages for 24 weeks, with supplementary copper and iodine being administered by injection. In Expt 2 young sheep were individually fed the two forages indoors at equal D.m. intake.Animals grazing kale in Expt 1 showed the characteristic symptoms of haemolytio anaemia from ruminal fermentation of S-methyl cysteine sulphoxide (SMCO) (Smith, 1974). This was most severe over the first 6 weeks, during which live-weight gains were very low (250 g/day). In the absence of copper supplementation animals grazing kale showed symptoms of copper deficiency. This was characterized by live-weight gain remaining low throughout the experiment (mean 280 g/day), rapid depletion of liver copper reserves, progressive reductions in serum copper concentration, reductions in erythrocyte copper and reduced glutathione (GSH) concentrations and a massive hepatic accumulation of iron. Copper deficiency only slightly lowered heart muscle copper concentration in kale-fed cattle, and this was counteracted byheart hypertrophy. The major effects of copper deficiency in kale-fed cattle were in erythrocytes, and a metabolic diagram is presented showing these effects to be biochemically similar to those produced by ruminal fermentation of SMCO.Copper supplementation of animals grazing kale increased live-weight gain (mean 425 g/day), reduced Heinz body formation, allowed the animals to recover gradually from the haemolytic anaemia and prevented other symptoms of copper deficiency. In contrast, animals grazing ryegrass-clover pasture showed only a very mild depletion of copper, there being no response in live-weight gain to copper supplementation.Activity of the enzyme glutathione peroxidase (GSH-Px) in whole blood was dependent upon blood selenium concentration in cattle fed both diets. In cattle fed on kale, bub not on pasture, reductions in erythrocyte GSH due to ruminal fermentation of SMCO and to copper deficiency were also associated with depressed blood selenium status.Glucosinolates were present in the kale (11μM/g D.M.) but absent from the pasture diet. Despite this, neither T4 production from the thyroid gland nor the conversion of T4 to T3 appeared to be impaired by kale feeding in either Expt 1 or Expt 2. In Expt 1 serum T3 concentration was better relatedto live-weight gain than was serum T4 concentration, in accord with T3 being the active form of the thyroid hormone.It is concluded that supplementation with copper but not iodine is essential where growing cattle are fed sole diets of kale for periods in excess of 12 weeks

Description: SUMMARYThe aim of the experiments reported here was to investigate the possibility of minimizing yield losses due to late sowing by increasing leaf area and radiation interception during the pre-flowering period. The use of large seed did increase leaf area, radiation interception and crop weight at flowering. Normally this would be expected to lead to increased yield of late sowings, but hot, dry conditions severely affected all crops during seed growth. Applying fertilizer nitrogen in the seed bed boosted pre-flowering growth of early but not late sowings, probably because low temperatures prevented a response in the latter. Increasing plant population density did improve leaf cover and radiation interception until just before flowering, but leaf canopies in late-sown, low density crops were then able to expand more and function for longer owing to less shading by flowers and pods. Seed retention was improved and, even with as few as 8 plants/m3 in 1973–4, a worthwhile yield was still obtained.

Description: Maize grain production in Nigeria is the collective effort of several growers individually cropping small areas. In these farms, maize stands are at suboptimal densities, soil fertility is low and crop loss from pests is high. Consequently, grain yields are characteristically low. By planting maize at closer spacing than the current standard, 90 x 25 cm, Fayemi (1963), Chinwuba (1967), and Okigbo (1972) were able to raise grain yield. However, the effect on pest population in Nigeria of increasing host plant density has received little research attention. Cromartie (1975) showed that host plant density and arrangement affect insect population dynamics. Other reports by Ficht (1932), Finch & Skinner (1976), Ralph (1977), Zepp & Keaster (1977), Adesiyun (1978) and Mayse (1978) indicate differential insect colonization, establishment and damage on host plants sown at different densities.

Description: SUMMARYIn a study of two breed groups, coarse wool Barki and ⅜ Merino ⅜ Barki, data were obtained on skin histology from birth to the age of 1 year, birthcoat fibre type arrays and fibre-follicle relationship.The ⅜ Merino exceeded Barki lambs in the maximum S/P ratio, values of which were 3·40 and 5·64 obtained at 6 and 8 months in Barki and ⅜ Merino respectively.Internal diameters of primary follicles ranged from 39·0 to 64·7 and from 41·0 to 56·8 μm; those of secondaries ranged from 19·8 to 34·9 and from 22·6 to 33·3 μm in Barki and ⅜ Merino respectively.The ratio of primary to secondary follicle diameters showed high values in both breed groups; averages were 1·89 and 1·71 for internal diameter and 1·86 and 1·71 for external diameter in Barki and ⅜ Merino respectively.Birthcoat fibre type arrays were mostly saddle, only 8·3% were plateau (P3) in both breed groups.In Barki primary centrals grew halo hairs, super sickle (A, A′, B), primary laterals produced super sickle (A, A′, B), sickles, coarse and medium curly tips, and secondaries mostly grew medium and fine curly tips and histerotrichs.In ⅜ Merino primary centrals produced halo hairs, super sickle (A, A′, B), primary laterals grew super sickle (A, A′, B), sickles, medium curly tips, and secondaries produced medium and fine curly tips and histerotrichs.

Description: SUMMARYAutomatic plot covers were used in a study of the effects of drought on the yield and water use of two spring wheat genotypes. The experiment tested the effects of drought at different stages of growth on yield and yield components. There was complete control over the water supplied to the plots, and a fully irrigated control treatment was included.The yields of the two genotypes were similar under fully irrigated conditions, but the yield components differed: Highbury had more grains per ear and TW 269/9/3/4 more ears per unit ground area and a higher mean grain mass. An early drought, which began 4 weeks before anthesis, caused a reduction in number of grains per ear in Highbury, which was outyielded by TW 269. Late drought also reduced yields differentially, reducing mean grain mass, and hence grain yield, more in TW 269 than in Highbury. Total shoot dry matter and grain yield were found generally to increase as water use increased. The average water use efficiency was found to depend upon the genotype and treatment.

Description: SUMMARYIn Expt 1 40 lactating British Friesians, 20 cows and 20 heifers, were used to study the effect of crude protein (CP) content of the whole ration on milk yield, milk composition and live-weight change when maize silage was fed as the basal ration. There were four treatments with five cows and five heifers on each. During lactation weeks 4–12 the cows on treatments 1, 2, 3 and 4 all received 7 kg maize silage dry matter (D.m.) plus 8 kg D.m./day of a concentrate containing either 14, 18, 22 or 24% CP, respectively; heifers received 1 kg/day less of both silage and concentrate. This produced whole-ration CP contents of 11·7, 13·9, 16.·0 and 17·1%. In the subsequent lactation weeks 13–20 silage feeding was increased to 9 kg D.m./cow/day and concentrate feeding decreased to 5 kg D.m./cow/day. Heifers again received 1 kg/day less of both silage and concentrate. This decreased whole-ration CP contents to 10·5, 11·7, 12·9 and 13·4%.During lactation weeks 4–12 and 13–20, with the exception of milk fat content in weeks 13–20, there were significant linear effects of whole-ration CP content on milk yield, milk fat, protein, lactose and total solids. There were no significant curvilinear relationships. Thus, despite the fact that the highest numerical values were generally recorded for the animals on treatment 3, the results indicate that a whole-ration CP content of at least 17·1 and 13·4% are required in early and mid-lactation respectively.In Expt 2 the loss of D.m., acid-detergent fibre and nitrogen from maize silage suspended in nylon bags in the rumen was measured. Compared with feeding either a low or high protein supplement, losses were greater for silage fed alone. If it is accepted that nitrogen loss can be approximated to protein degradability, then the value for maize silage was between 0·6 and 0·7. Using the same technique in Expt 3, comparable nitrogen losses for fish meal, decorticated groundnut meal and soya-bean meal were 0·3, 0·9 and 0·9, respectively, after 24 h incubation.

Description: Research has shown that it is now possible to control the oestrous cycle of ewes with a high degree of precision (Robinson et al. 1967; Gordon, 1975; Boland, Kelleher & Gordon, 1978). There is general agreement that a high concentration of progestagen, followed by rapid withdrawal and adequate ovarian stimulation is necessary for acceptable fertility (Robinson et al. 1967; Gordon, 1975; Colas, 1975). Application of artificial insemination in France has involved the use of a 40–45 mg Cronolone sponge (Cognie, Mariana & Thimonier, 1970; Colas et al. 1973) while controlled breeding in sheep in Ireland has been used in conjunction with a 30 mg Cronolone pessary (Gordon, 1975; Smith, Boland & Gordon, 1978, 1981). The present experiment was designed to compare the relative effectiveness of two doses of Cronolone (30 or 45 mg) when administered in conjunction with two quantities(375 or 750 i.u.) of pregnant mare serum gonadotrophin (PMSG), given by intramuscular injection.

Description: SummarysLabelled fertilizer N (15N depleted ammonium sulphate) was used to investigate both soil and fertilizer N use by winter wheat established in contrasting seed beds, these being soil cultivated to 20 cm depth or left undisturbed. The crop's response to, and recovery of, a range of N levels from 0 to 280 kg/ha given as a divided application in spring, were measured over two seasons. It was found that during the first season the direct-drilled wheat took up, on average, more fertilizer N but less soil N than wheat in cultivated soil, probably through differences in organic-matter mineralization. The different cultivation systems produced similar grain yields at all rates of applied N; however, when no fertilizer N was given, dry-matter production and soil-N uptake by the crop in the undisturbed soil were substantially less than by the crop in the cultivated soil. Crop recovery of the fertilizer N at harvest was between 29 and 40% of that given. After harvest, an average of one third of the applied fertilizer N was found in the top 60 cm of the soil profile. In the following season on the same plots a second winter wheat crop, receiving no fertilizer N, was drilled. At harvest there was shown to be an increase in grain yield and soil- and fertilizer-N uptake at the higher srates of N given in the previous season. In spite of this the recovery of the labelled residues was small, no more than 6% of the original application, or 15% of the residues remaining in the soil, irrespective of cultivation system.

Description: SUMMARYThe effects of treading and the return of excreta on a Lolium perenne-Trifolium repens sward defoliated by sheep set-stccked at high and low stocking rates were examined. Sward performance was measured inside ‘graze-through’ cages which allowed defoliation without treading and excreta return, and outside where sheep grazed either fitted with harness to prevent the return of excreta or unharnessed to allow the normal return of excreta. Live-weight gain was measured from excreta return and non-return swards. The treatments imposed had large effects on herbage growth and botanical composition.At a stocking rate of 25 yearling wethers/ha, sheep excreted about 1·1 kg N/ha/day, which increased soil N and led to an increase in herbage growth of about 26 %. The return of excreta increased ryegrass tiller density and this was partly responsible for a 26% reduction in the proportion of clover in the sward; the weight of clover was 13% loss where excreta were returned, and on this treatment stolon length at the end of the experiment was similar to that at the beginning. Doubling the stocking rate increased the N returned via excreta to about 1·3 kg N/ha/day, and this increased herbage growth by 53% but suppressed the proportion of clover by 21%, though not the weight of clover. Clover stolon length decreased during the experiment at this stocking rate, both with and without the return of excreta. Sheep live-weight change benefited from the stimulus to herbage growth where excreta were returned at the high stocking rate, but not at the low stocking rate.Treading by 25 sheep/ha increased soil compaction but had no significant (P 〉 0·05) overall effect on herbage growth and botanical composition. However, treading by double the number of grazing animals significantly reduced herbage growth by 10%, plant root weight by 47% and the proportion of clover in the sward by 11%.Differences in sward performance between stocking rates were due more to the difference in defoliation intensity between these stocking rates than to either treading or the return of excreta.

Description: SUMMARYThe digestibility and rumen metabolism of diets containing as 50% of their organic matter (OM), cotton straw (CS) untreated, treated with sodium hydroxide and treated with ozone, were studied in sheep cannulated in the rumen and at the duodenum with simple cannulae. The concentration of total volatile fatty acids (VFA) in the rumen of sheep given the ozone and NaOH treatments was higher than in the untreated diet; however, the VFA profiles were not different. The rumen dehydrogenase activity, suggested to reflect general microbial activity, was higher by 83 and 81% in the ozone and NaOH treatments respectively, than in the untreated.Apparent digestibility of organic matter in the ozone-treated diet was 74·6%; 1·25 and 1·17 times higher than in the untreated and NaOH-treated diets respectively. The calculated values for organic matter and cell-wall digestibilities of the cotton straw in the complete diets were: 30·0, 20·0; 60·8, 60·0; and 39·6, 39·7%, respectively, for the untreated, ozone and NaOH-treated cotton straw. Nitrogen metabolism was not impaired by the presence of formic acid in the ozonated cotton straw; the apparent absorption of N from the intestine and the apparent digestibility of N were higher in the ozonetreated diet than in the untreated or NaOH-treated diet.The proportion of organic matter and cell walls digested in the rumen was higher in the NaOH and ozone treatments than in the untreated, and the possible reasons for that are discussed. A positive relationship was found between cell-wall digestion in the rumen (% of intake) and the rate of passage (% per h) of particulate matter from the rumen. The interpretation of this relationship is discussed in general and in view of the results of the present study.

Description: SummaryIn four consecutive experiments, plasma uric acid (PUA), hepatic xanthine dehydrogenase (XDH) and body-weight gains (WG) of broiler chickens were measured under varying dietary methionine, protein and energy. In Expt 1, increases in WG with increasing dietary methionine peaked at 0·60%, a level where the initial decreases in either PUA or XDH reached a minimum. PUA and XDH in broiler finishers (Expt 2) decreased between 0·26 and 0·50% dietary methionine while WG improved between 0·26 and 0·50% methionine. XDH in the 18% protein and 0·68% methionine + cystine (MC) diet combination for Expt 3 was 66·4 μtmol/10 min/total liver weight, a value higher than either the 43·5 or 46·5 μtmol/10 min/total liver weight, respectively obtained in the 21% protein + 0·68% MC and 24% protein + 0·68% MC diet combinations. Both PUA and XDH, however, increased with increasing dietary protein when MC was either 0·76 or 0·84% diet. XDH in Expt 4 decreased between 11·7 and 13·4 MJ ME/kg diet that contained either 0·76 or 0·84% MC, tending not to vary between 13·4 and 15·1 MJ ME/kg diet. This enzyme activity remained essentially similar between 11·7 and 15·1 MJ ME/kg diet that contained 0·68% MC.

Description: SummaryFrom 1980 to 1982 fungicide and aphioide sprays were tested in factorial combination with four amounts of nitrogen fertilizer, applied in one or two dressings to winter wheat, on three contrasting clay soils. These experiments were at Hexton (Burwell series) in Hertfordshire, at Billington (Evesham series) and at Maulden (Hanslope series) in Bedfordshire, following a 2–year break, an all-cereal rotation, and continuous wheat respectively. The nitrogen dressings were calculated after taking into account mineral N in the soil. In 1981 and 1982 soil density was measured by penetrometer. This showed compaction in soil at Maulden 28 cm deep which caused waterlogging in spring; this delayed growth which was not made good later.At Hexton a small seed rate was used; plant losses during winter were proportionally larger than elsewhere. At Billington, the maximum number of stems occurred in March and elsewhere in April. Despite these differences in seed rate and number of plants, number of ears varied little, and each year the wheat at Hexton accumulated dry matter most rapidly. The growth rate there ranged from 20·0 to 21·8 g/m2/day during the linear growth phase as compared with 14·4 to 16·6 g/m2/day at the other two sites. Giving N in two dressings rather than in one increased dry-matter yield at all sites in May, but later this benefit remained static and so became a smaller proportion of the total. Fungicides increased post-anthesis dry-matter yield by 0·75 t/ha, most of which was incorporated in the grain.Mean grain yields from 1980 to 1982 where nitrogen fertilizer was given were 9·86 t/ha at Hexton, 7·88 t/ha at Billington and 6–91 t/ha at Maulden. Additional nitrogen fertilizer always increased grain yield when fungicides and aphicides were given, but not where they were not. Grain yields in excess of 10 t/ha were achieved with numbers of ears ranging between 360 and 435/m2. The components of yield showed that grain yield was related to the number of grains per ear and 1000·grain weight, but not number of ears. Grain weight was increased by 3·1 mg by the fungicides.The fungicides controlled the diseases eyespot (Pseudocercosporella herpolrichoides), Septoria spp. and yellow and brown rust (Pucdnia striiformis and P. recondita) where they occurred, but even where these diseases were absent or at very low levels the fungicides significantly increased grain yield. At Billington and Maulden take-all (Qaeumannomyces graminis) infected between 44 and 90% of the plants and sharp eyespot (Rhizoctonia cerealis) infected from 〈 1 to 20% of the stems because the wheat followed cereals. Yields of straw behind the combine-harvester were from 50 to 70% of those obtained from sheaves cut at ground level.

Description: Major economic losses in many agricultural crops have been attributed to damage caused by insects of Heliothis spp. For example, Alcock & Twine (1980) estimated that in Queensland, Australia the annual losses caused by Heliothis spp. were over $16 million, with major losses in sorghum, cotton, tomatoes, tobacco, and safflower. The increasing resistance of Heliothis spp. to pesticides together with an increasing awareness of environmental problems associated with excessive use of pesticides has encouraged the development of research into the area of host-plant resistance. Naturally occurring toxicants and repellants, feeding deterrents and sex pheromones have been evaluated for some years (Jacobson, 1982; Lukefahr, 1982).