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: SUMMARYCabbage accessions were screened for resistance to turnip mosaic (TuMV) and cauliflower mosaic (CaMV) viruses in glasshouse and field tests. None was immune to infection by either virus, but some were highly resistant to one or both viruses. TuMV induced severe necrotic lesions on the outer leaves of susceptible plants at harvest, and this was associated with severe internal necrosis in heads stored for 8 months at 0–1 °C. This correlation was not observed in CaMV infected plants. Pepper-spot necrosis was low in stored heads of some accessions but high in others.

Description: SUMMARYA high level of resistance to the bean common mosaic virus strains NL3 and NL4 when inoculated separately or together was confirmed in the cultivars Turkish Brown, Valja and 1750–73. Following crosses between the susceptible cv. The Prince and all three resistant cultivars, inoculation of F2 and F3 populations revealed that the cvs Turkish Brown and Valja each differed from The Prince in being homozygous for a major recessive gene conferring resistance to both NL3 and NL4. Homology tests indicated that the same gene was present in both Turkish Brown and Valja. Polygenes in Turkish Brown and Valja also appeared to confer some resistance to NL3, or environmental variation led to continuous distribution patterns in the F2's of resistant parents crossed with The Prince. Although a major recessive gene controlled resistance to NL3 in cv. 1750–73, it differed from that in the two other resistant cultivars. In addition, cv. 1750–73 carried a dominant gene determining reaction to the virus; probably the I gene originally found in Corbett Refugee. An attempt is made to relate these results to Drijfhout's (1978) gene-for-gene model. Using Drijfhout's gene nomenclature all the cultivars tested appear to carry the strain nonspecific gene bc-u. Further genetical tests will be necessary to determine with certainty which, if any, of Drijfhout's strain-specific resistant bc-genes are present in the three resistant cultivars studied here.

Description: SUMMARYIn St Vincent, West Indies, the yellow passionfruit (known as Passiflora edulisf. flavicarpa Degener, but probably specifically distinct from P. edulis Sims) is grown commercially and is pollinated by the indigenous bee Xylocopa mordax Smith. The diel patterns of anthesis and nectar availability are described and related to the timing of bee visits and pollination. Flower-bagging experiments confirmed that the setting of fruit depended on cross-pollination, was prevented by exclusion of flower visitors, and was sometimes limited in the field by inadequate pollination.Bees collected Passiflora nectar, and evaporated it on their tongues from 45–50 % to 62–63 % sugar before storing it. But the Passiflora pollen deposited on the bee's dorsum was groomed off and rejected; only Gliriddia pollen was used for bee bread. Thus the bees treated ‘acceptable’ (Gliriddia) pollen and ‘unacceptable’ (Passiflora) pollen differently, and since pollen unacceptability improves the pollen's chance of reaching a stigma, it may be a widespread adaptation.The yellow passionfruit flower shows many features characteristic of tropical Xylocopa flowers. Here, as elsewhere, this introduced crop depends for its pollination on indigenous bees which, though suitable morphologically and behaviourally, are not abundant enough to cause a high proportion of flowers to set fruit. The setting of fruit might be improved by increasing bee populations through provision of more timber for nestsites, and suitable flowers to supply pollen and nectar throughout the year.

Description: SUMMARYThe joint action of several insecticide formulations with a constant concentration of the antifeedant Du-ter that gives 50% starvation with the fourth instar of Spodoptera littoralis (Boisd.) was assessed. The results provided evidence that the toxicity of all the tested insecticides to the cotton leafworm can be markedly increased by using Du-ter in combination with each of the candidate insecticides. Since Du-ter proved to be highly synergistic, its mixtures with insecticides can result in a decrease in the rate of insecticide application.

Description: SUMMARYAn analysis is suggested for an experiment investigating plant competition between different genotypes grown in pure culture and in binary mixtures with unequal proportions of genotypes. Worked examples are presented.

Description: SUMMARYDuring a period without rainfall the upper layers of the soil may become dry whilst the lower layers provide sufficient moisture for the plant to continue growing. In experimental conditions simulating such a soil environment, new main root axes ceased to be produced by plants of perennial ryegrass. Shoot growth and leaf elongation rate were little affected during the first 2 weeks of the treatment. The subsequent introduction of moisture round the base of the plant resulted in the rapid production of new root axes and increase in the leaf elongation rate. Although there was considerable intra-varietal genetic variation in the rate of development of new root axes and leaf elongation after wetting it is concluded that this would be of doubtful value as a selection criterion.

Description: SUMMARYSixty-one experiments with 15 levels of K fertilizer in the presence of excess N and P fertilizer were carried out on adjacent sites of the same field. Yield was always related to level of K fertilizer by a ‘diminishing returns’ type curve, and a derived equation, which defined relative responsiveness in terms of a single parameter, fitted the data for each crop very satisfactorily. Although the responsiveness of many of the crops was similar there were marked differences and the optimum levels of K (defined as the level at which a further 10 kg/ha increased yield by 1%) varied from 0 to 360 kg/ha, depending on the crop. Responsiveness was largely independent of the plant family to which the crop belonged, but was related to the mean plant weight atharvest; the larger the weight the less reponsive the crop. No general relation existed between responsiveness and duration of growth.The % K in the dry matter of leaves (including stems) at harvest of crops receiving the optimum levels of K fertilizer was mainly determined by the family. It was generally between 0·9 and 1·1 for the Amaryllidaceae, between 1·1 and 1·2 for the Leguminosae and between 1·9 and 2·5% for the Cruciferae. The difference between the % K in the dry matter with the optimum level of K fertilizer and that with no fertilizer was proportional to responsiveness. Percentage K at harvest was a good indicator of the extent to which crop growth was restricted by lack of potassium.At harvest crops receiving the optimum levels of K fertilizer contained between 29 and 220 kg/ha of K, but uptake increased asymptotically to a maximum as K applications were raised to higher levels. Maximum uptake for nearly all crops was almost double the uptake with the optimum fertilizer application.Percentage recovery of 100 kg/ha of added K fertilizer varied between 8 and 70%, roughly in proportion to the total crop dry weight, which varied between 1 and 15 t/ha.Effects of level of K fertilizer on crop quality were also measured and over the practical range of applications the effects were generally small.The differences between the K requirements of crops are discussed and it is argued that the responsiveness of one crop relative to that of another would be expected to be similar on a range of soils.

Description: SUMMARYData for 383 steer carcasses from the first 3 years of the Meat and Livestock Commission's Beef Breed Evaluation programme were used to evaluate a standardized commercial cutting technique for estimating breed differences in carcass composition. The sample included carcasses from cattle out of Friesian, Hereford × Friesian and Blue-Grey dams by sires of the main traditional British beef breeds and by Charolais, Limousin and Simmental sires. The left side of each carcass was divided into 14 standardized commercial joints which were deboned and trimmed of fat to a fixed level (commercial cutting); the other side was jointed in the same way and each joint fully separated into lean, subcutaneous fat, intermuscular fat and bone (full separation). Breed means for characteristics obtained by commercial cutting were adjusted to equal carcass subcutaneous fat percentage (SF) estimated by visual appraisal, while those for full separation characteristics were adjusted to equal SF obtained by tissue separation. Breed differences in deboned fat-trimmed joints (saleable meat) as a percentage of carcass weight were in good agreement with those for carcass lean percentage (between-breed correlation, rb = 0·92), as were those for saleable meat to bone ratio and lean to bone ratio (rb = 0·91). There was a poorer relationship between fat trim and separable fat (rb = 0·62) but there was little breed variation in these characteristics at equal SF. Breed differences in the percentage of total saleable meat distributed in higher-priced joints were very similar to those for lean distribution in higher-priced joints (rb = 0·87).

Description: SUMMARYThree ewes were intraduodenally infused with yeast RNA (15, 20 and 30 g/day) or control solutions for 3 days and the net changes in urinary allantoin excretion determined. Four mature wethers fitted with a re-entrant cannula in the proximal duodenum were fed two levels (0·66 and 1 × maintenance) of pelleted lucerne hay. Allantoin excretion was compared with total nucleic acid (NA) flow in the small intestine.The average proportion of the recovery of the infused RNA-N dose as urinary allantoin–N amounted to 0·119 ± 0·0046. The values of the net increase of allantoin-N (Y, g/day) above control levels were highly significantly correlated (n = 12, r = 0·98) with amounts of RNA-N infused (X, g/day): y = 0·1185 (± 0·0086) X–0·004 (P 〈 0·001). The average ratio of urinary allantoin-N to NA-N passing the duodenum during 24 h was 0·173. A difference between the two conversion factors is discussed in relation to endogenous allantoin excretion and purine base composition of yeast and bacterial RNA.

Description: SUMMARYThis study was carried out to investigate the effect of crossing the subtropical fat-tailed Ossimi (O) sheep with the Hampshire (H) on ewe and lamb performance. Data used involved 457 ewe records of Ossimi, Hampshire and four crosses, and 404 lamb records of Ossimi and five crosses.Hampshire ewes performed less well than the local Ossimi ewes in various reproduction traits. They weaned 0·26 lamb/ewe run with the rams compared with 0·82 from the local ewes mated to Hampshire rams. The Hampshire ewes seemed to be anoestrous during the first part of the normal breeding season of the local ewes (May–July). Different Hampshire–Ossimi cross-bred groups showed better ewe reproduction performance than the purebred Hampshire ewes, but were inferior to the Ossimi. The first cross ewes were, generally, the best among all the cross-bred ewes and the reproduction performance declined with increasing percentage of Hampshire genes. When the first cross was interbred, ewe performance declined clearly in the F2. All cross-bred groups of ewes gave significantly heavier annual greasy-fleece weight than Ossimi ewes.The only lamb performance trait that was improved by up-grading the Ossiroi sheep with the Hampshire breed was the first greasy-fleece weight, while lamb survival and weaning weight were clearly decreased with the advance of up-grading.The recombined cross-bred groups ( and ⅝ Hampshire) proved to be the best cross-bred and showed considerable improvement in lamb performance traits over the local Ossimi sheep, except for lamb survival.It is concluded that crossing Ossimi sheep with the Hampshire improved only fleece weight but not lamb production.

Description: SUMMARYFour genotypes of dry beans were compared at three planting dates during one season (April to June, 1976) and four planting dates during a second season (November 1976 to January 1977). Yield declined with delay in planting in both seasons but in the second season yields were lower at the first planting and declined less rapidly. Canadian Wonder was the most stable-yielding genotype and had highest mean yield though it may have been inferior to other genotypes at the two most favourable plantings. Its stability was attributed to drought escape and good field resistance to drought and disease. Mexican 142 was the least stable genotype. A black-seeded landrace yielded well in dry conditions in spite of its long duration.The most important components determining planting date effects on yield were numbers of pods per plant and seeds per pod. Canadian Wonder had markedly more stable numbers of pods than any other genotype.Cooler temperatures in July and August retarded crop development in the first season. For one planting of the second season, flowering was retarded by 7–10 days in all genotypes and this was apparently an effect of water shortage. No effect of water was apparent on the time taken from flowering to maturity.

Description: SUMMARYThe performance of Suffolk cross-bred ewe lambs produced either by Suffolk crossbred ewes, 70–90% Suffolk (HS), or by Ossimi ewes, 35–45% Suffolk (LS), was investigated. Forty-three ewe lambs from both groups were available, and were given two different levels of feeding.The LS ewe lambs showed, insignificantly, better growth performance than the HS group, and breed group differences increased with age. They also reached puberty earlier (305·4 v. 334·6 days for the HS ewe lambs). Using the HS breeding rams rather than the imported Suffolk ones, for improving lamb production from the local sheep flocks, is recommended.The LS ewe lambs started their first breeding season 18 days earlier, and ended 34 days later, than the HS ewe lambs. Both cross-bred groups showed clear anoestrous periods of 225·4 and 202·2 days, respectively. The onset of their second breeding season was similar, on average 29 August. These figures are close to those of the purebred Suffolk ewes, and far away from the nonseasonal local parents.

Description: SUMMARYThe aims of this work were to determine the feasibility of using the incorporation of radio-labelled thymidine into fat cell DNA in vivo as an index of cell division in the adipose tissue of young pigs, and to distinguish between the processes of new cell synthesis and the ‘filling’ of existing ‘empty’ cells.Five Large White pigs were given tritiated thymidine as follows: two animals were injected at 2 days of age, two at 9 days of age and one at 40 days of age. The animals were killed at different times after the injection and adipose tissue was removed from various sites. The tissue was separated, using collagenase, into ‘fat cell’ and ‘stromal cell’ fractions. The specific (radio)activity of DNA isolated from each fraction was measured.Fat cell synthesis occurred rapidly in pigs aged between 2 and 40 days of age. It appeared that by 40 days of age the rate of synthesis declined in backfat such that the filling of pre-existing empty fat cells became a more important contributor to the increased mass of adipose tissue than the filling of newly synthesized cells.

Description: SummaryNinety triple test cross (TTC) families and 32 varieties of spring wheat (used as parents in TTC programme) were raised in three randomized blocks in 1977–8 and 1978–9 to detect additive, dominance and epistatic components of genetic variation and genotype x environment interaction at both micro- and macro-environmental levels for five quantitative traits: final plant height, spike length, number of spikelets per spike, 100-kernel weight and grain yield per plant. Epistasis was an important element for yield per plant in both years. But, absence of significant epistasis was observed for two component traits of yield, namely, spike length and number of spikelets per spike, in these 2 years. Dominance was directional in all cases. Additive gene effects were most sensitive to micro- as well as to macro-environmental differences.

Description: SummaryData from 266 pregnancies of 144 Finn x German Mutton Merino and Finn x Awassi ewes were used to determine the effects of season of mating, dam and sire breeds, litter size and sex of the offspring, and age of the ewe on the duration of gestation.June, September–October and January matings resulted in significantly different durations of gestation of 143·3, 145·3 and 146·1 days, respectively.Suffolk rams’ matings resulted in a significantly shorter gestation than matings with German Mutton Merino, Schwarzkopf or cross-bred rams.A highly significant linear regression (b = –0·80) of the duration of gestation on the number of lambs was found.Male lambs were carried longer than female lambs.The intraclass correlation between the gestation periods for lambs which were maternal half-sibs was highly significant.

Description: SummaryA survey of sheep production was undertaken in rangeland areas of western Afghanistan to provide basic information of ewe body-weight changes throughout the year and on production variables, including mortality and lambing performance. Ewes lost up to 31% of body weight between December and March and mortality over the same period was 7%. On the basis of the results of this survey, an experiment was made to test the effect on lambing performance of pre-lambing supplementation of range-based ewes.Supplementation reduced weight losses in ewes, but the feeding treatments did not produce significant results in terms of lamb birth weights or survival to 10 days. However, there were indications that selective feeding of weak ewes can produce economic benefits, given that the costs of supervising such animals are minimal and the price of grain supplements is low relative to the price of meat.

Description: SummaryTwo breed comparisons were made: (a) between Galway and Galway x Finnish Landrace (Fingalway) lambs, and (6) between Galway x Fingalway and Galway x (Finn x Texel) lambs, for the melting point and fatty acid composition of subcutaneous tail, subcutaneous 13th rib and perinephric fat. The lambs were slaughtered at market weight from September to January, being finished off on grass except for a small number finished indoors on concentrates and hay.Slaughter age and carcass weight, both of which had significant effects on some of the measurements, were included as covariates in the breed comparisons. Overall breed effects were small. The melting point of the fat from Fingalway lambs was lower than that of the Galway breed in each location, the difference being significant for subcutaneous rib fat. This was associated with a lower concentration of stearic acid and a higher concentration of oleic acid in each fat depot of the Fingalway breed, the difference being significant for oleic in subcutaneous tail and for stearic in subcutaneous rib fat. No significant breed differences or trends were observed for the other fatty acids measured. Results for a small number of pure Finn lambs supported the Finn ancestry influence indicated by comparison (a). In the second breed comparison, no significant breed differences were observed, the values being close to those obtained for the pure Galway lambs.

Description: SummaryThree experiments each utilizing four buffalo heifers in 4 × 4 latin square designs were conducted over a period of 84 days to estimate the voluntary consumption of eight long-chopped and four ground roughages. Voluntary intake and rate of passage were determined during the last 10 days and digestibility of feed nutrients during the last 6 days of a 21-day experimental period.The mean daily dry-matter intake (DMI, g/kg W0·75), D.M. digestibility (%) and mean retention time (h) of long and chopped foods were 81·6, 65·7, 75·2; 81·4, 54·2, 60·3; 78·0, 58·6, 66·0; 75·8, 58·5, 66·3; 67·5, 68·1, 87·9; 62·1, 40·9, 73·3; 56·3, 50·6, 70·9 and 55·5, 58·8, 82·4, respectively for maize silage, sorghum stover, dry grass, maize stover, berseem hay, wheat straw, pearl-millet stover and cowpea hay. Appreciable differences were observed between feeds in the digestibility of D.M., organic matter (OM) and crude protein (CP). No consistent pattern in level of intake and either CP or crude fibre (CF) contents of feeds or their D.M. digestibilities was discernible. The relationship between DMI and D.M. digestibility was low (r = 0·29). Higher DMI of feeds tended to be associated with faster rate of passage excepting maize silage and berseem hay. The relationship between D.M. digestibility and mean retention time was low (r = 0·46) and between total digestible nutrient intake and body weight was high (r = 0·79).The mean daily DMI (g/kg W0·75), D.M. digestibility (%) and mean retention time (h) of ground roughages were 68·7, 51·3, 58·0; 62·9, 38·4, 60·0; 62·4, 40·1, 63·0; 53·1, 66·6, 72·0, respectively for ground maize stover, wheat straw, dry grass and berseem hay. Ground roughages appeared to be utilized less efficiently by buffaloes than longchopped roughages.

Description: SummaryA urine collection system suitable for male pigs is described. The system was tested by the recovery from urine of an intravenous infusion of51 chromium as the EDTA complex. Recovery from four pigs was 99·2 ± 1·6%.

Description: SummaryAn intercropping experiment is described in which three plant population densities of an early sorghum (82 days) were factorially combined with three plant population densities of a later-maturing pigeonpea (173 days) in a standard 2 sorghum:1 pigeonpea row arrangement. Sorghum growth was not affected by the presence of pigeonpea, and the farmers' primary objective of maintaining a ‘full’ sorghum yield was achieved if the density of the intercropped sorghum was equivalent to the sole crop optimum.The spatial distribution of roots after 30 and 60 days of growth did not appear to be altered by intercropping, and roots of the two crops were found to intermingle freely.

Description: SummaryAn index of feather cover is described and applied to assess the coats of various birds. Feather area indices were calculated, by analogy with the leaf area index used by crop ecologists, as the projected area of feathers above unit area of skin. Measurements were made on samples from chickens, turkeys, pheasants, sparrows and herring gulls. The index was calculated for feather tracts on six areas of the body. An overall area index was also calculated, based on the feather cover of at least 60% of the bird's body surface. Intra- and interspecific differences were large. Between species there was a positive correlation between feather index and body weight, while within species, for poultry at least, the opposite was found. This characterization of the feather coat is discussed in terms of its possible use as an index of the insulation of feathers.

Description: Vicia faba, in common with other grain legumes, rarely gives economic yield increases in response to soil application of nitrogenous fertilizer either before sowing or at flowering (McEwen, 1970a, b; Day, Roughley & Witty, 1979). The lack of response was attributed to poor uptake of the applied fertilizer particularly at flowering (Day et al. 1979). Garcia & Hanway (1976), however, increased the yield of soya beans from 3695 to 5225 kg/ha with foliar sprays containing N as urea, P, K and S applied during the seed-filling period. Day et al. (1979) using four foliar sprays of the same composition increased yield of V. faba by 361 kg/ha (8·6%) following the uptake of 15% of the 80 kg N/ha applied. However, Robertson, Hinson & Hammond (1977) reported no yield responses of soya beans with up to five foliar sprays of the same composition and noted that those containing ammonium polyphosphate and KNO3 caused leaf damage that significantly reduced yield.

Description: SummaryIn two field experiments with winter wheat varieties, the grain yields per unit area calculated from entire plots 4·2 × 1·18 m were 25% greater than the yields of the centre row. This occurred mainly because the outer rows in the plots yielded 62% more than the centre row. When the yields were calculated on the basis of a plot width of 1·53 m (the distance from path centre to path centre across the long axis of a plot), it was estimated that they were 4% less than the yields of the centre rows. In the most extreme case when a short variety in a plot of this size was bordered by neighbours 70 cm taller, its yield, relative to that of the tall variety, was underestimated by 10–12%.A separate experiment showed that the greater yield from plants at the edges of plots was associated mainly with more ears.

Description: Urea is not efficiently utilized by ruminants mainly because of its more rapid (about 4 times) rate of hydrolysis than the corresponding uptake of ammonia by the rumen microbes (Bloomfield, Garner & Muhrer, 1960). A number of attempts have been made to slow down the release of ammonia either through the production of urease immunity (Sidhu, Jones & Tillman, 1968) or by complexing urea with starch (Deyoe et al. 1968) or with molasses (Chopra et al. 1974). The present communication reports the method of preparation and in vitro breakdown of urea-hemicellulose complex.

Description: SummaryExperiments were carried out to assess the increase in yield potential of winter wheat in the U.K. due to variety improvement since the early years of this century. The effects of other genetic changes were minimized by applying fungicide to control eyespot and foliar diseases, and by using nets to prevent lodging. The experiments were carried out in 1978 at Cambridge. One, on soil of high fertility in Camp Field, received 104 kg N/ha and the other, on soil of lower fertility in Paternoster Field, received 38 kg N/ha. Twelve genotypes were tested. Eight were varieties which formed a chronological series beginning with Little Joss, introduced in 1908. The remaining genotypes were recently developed selections from the Plant Breeding Institute and a line bred by the French breeders, Benoist.The average yield of the 12 varieties and lines tested was 3·96 t/ha in Paternoster Field and 6·40 t/ha in Camp Field. In both fields the two highest yielding entries, Hobbit and the advanced breeding line 989/10, outyielded Little Joss by close to 40%. Benoist 10483 was the only entry for which the percentage yield advantage depended on high soil fertility.The newer, high yielding, varieties were shorter and reached anthesis earlier than the older varieties. They had lower stem weights/m2 than the older varieties but similar maximum leaf area indices and leaf weights/m2. Within each experiment the total dry-matter production of the varieties was similar, the increase in grain yield due to variety improvement being associated mainly with greater harvest index (ratio of grain yield to grain + straw yield).It is argued that by a continuation of the trend towards reduced stem length, with no change in above-ground biomass, breeders may be able to increase harvest index, from the present value of about 50% to about 60%, achieving a genetic gain in yield of some 25%. As the limit to harvest index is approached, genetic gain in yield will depend on detecting and exploiting genetic variation in biomass production.

Description: SummaryTwo experiments were made, each with 35 autumn-calving cows fed on complete diets containing 40–70% hay and 60–30% concentrates. In both experiments, cows fed to appetite on a diet containing 11 MJ metabolizable energy/kg D.M. for weeks 7–24 of lactation ate about 20% more than cows rationed according to yield, but produced only about 3% more milk. The cows fed to appetite gained more in live weight, but lost their weight advantage during the subsequent grazing season.In Expt 1, a further group of cows were fed to appetite on diets progressively reduced in metabolizable energy content from 11·0 to 9·2 MJ/kg. Dry-matter intake decreased by about 1·2 kg/day per 1 MJ reduction in energy content. The lower dry-matter and energy intakes of cows on this treatment did not significantly reduce their milk yield, but their response when turned out to grass suggested under-nutrition in late winter. In Expt 2, increasing the energy content of the diet in early lactation (weeks 7–12) and reducing it thereafter had no significant effect on milk yield.Within each treatment group there were reasonably close relationships between energy intake and energy requirement. Nevertheless, it seems likely that the efficiency of feed utilization of cows fed on complete diets will be low unless intake is controlled by energy dilution.

Description: SUMMARYIn Expt 1, lactating dairy cows grazing kikuyu grass (Pennisetum clandestinum) were given no supplement (C), supplements of rolled barley grain at 4 (4R) and 6 (6R) kg/day and supplements of NaOH-treated whole barley grain at 4 (4A) and 6 (6A) kg/day. Daily production of milk (kg/day), fat and protein (g/day) and live-weight changes (g/day) respectively were C 7·82, 303, 276, 450; 4R 9·26, 338, 315, 865; 4A 10·23, 366, 349, 529; 6R 10·09, 352, 343, 672; 6A 10·61, 363, 348, 361.Milk production was significantly higher (P 〈 0·05) and live-weight gain significantly lower (P 〈 0·05) on NaOH-treated grain than on rolled grain.In Expt 2, yearling steers in pens were fed pasture hay ad libitum with no supplement (C) and 3 kg/day of barley grain which was either rolled (3R) or NaOH-treated whole grain (3A). Mean intakes of hay (g/day) and DOMD in vivo (%) respectively were C 7684, 60; 3R 5224, 65; 3A 6209, 60.Hay intake was significantly higher (P 〈 0·05) on NaOH-treated grain than on rolled grain.Fractional disappearance rates of rolled and NaOH-treated grain from nylon bags suspended in the rumen were, respectively, 0·15 and 0–07/h for the period 0–4 h, and 0·07 and 0·02/h for the period 4–12 h incubation. In Expt 2, rumen pH was higher and the digestion rate of hay in nylon bags in vivo was higher on C than on 3R and 3A. Volatile fatty acid (VFA) concentrations in the rumen did not differ significantly between diets.It was concluded that greater milk production and hay intakes when cattle were fed NaOH-treated whole barley than when they were fed rolled barley were attributable to the slower rate of digestion of the former. The NaOH treatment (30 g NaOH/kg grain) was probably too low and further study is necessary to determine optimum levels of treatment, which are likely to vary with the ratio of grain: forage in the diet.

Description: SUMMARYEating behaviour and the diet selected by cattle progressively defoliating a crop of Lablab purpureus cv. Rongai were measured in three periods each of 12 days. Crop composition during defoliation was recorded.At the beginning of grazing the crop contained 2230 kg green leaf/ha but after 12 days' grazing the crop contained only 300 kg/ha. In the first 6 days cattle selected a diet which contained 85% green leaf but after 12 days' grazing the selected diet contained only 17% green leaf. As available leaf declined, grazing time increased from 465 min on day 1 to 685 on day 6 before declining to 490 min on day 12. Maximum grazing time occurred with a green leaf yield of 1185 kg/ha. The number of eating bites increased from 26000 to 44500 between days 1 and 6 and then declined to 30000 after 12 days' grazing. Grazing time and the number of eating bites were significantly correlated (r = 0·99).Bite size declined from 410 mg organic matter (OM)/bite on day 1 to 90 mg OM/bite on day 12. This decrease in bite size caused a linear decline (927 g/day) in estimated organic-matter intake. The rapid decline in bite size and intake was caused by the reduction in the quantity of leaf per unit area and the lack of desire of cattle to eat stem.It was concluded that the desire of cattle to select leaf is so strong that stem yield should be largely disregarded when considering Rongai as a grazing crop.

Description: SUMMARYThe effect of three different growth rates from 15 to 40 kg live weight on some offal components 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 of weight stasis, which was followed by ad-libitum feeding. In each treatment, two animals were killed at 25, 30 and 35 kg and three animals at 40 kg. Analyses of covariance were used to compare linear regression equations representing results from each treatment using the logarithmic transformation of the allometric equation, y = axb.Differences between treatments were found for the weight of certain non-alimentary tract offals including the liver (H, HMH 〉 L), kidney (H, HMH 〉 L), skin (H, HMH 〉 L) and hind-hooves (H 〈 HMH, L). The slope of the regression for the heart, liver, kidney, and the combined trachea and lungs was greater in the HMH, than in the H, treatment. These differences in slope were attributed to a decrease in weight of each component in the HMH animals during weight stasis except for the lungs and trachea, where the greater slope was due to an increased weight of this component in the HMH animals killed at 40 kg.Fat-trimmed weights of the omasum, abomasum, small intestine and large intestine were greater in both the H and HMH animals than the L animals. The weights both of the rumen-reticulum and total alimentary tract (TAT) were less at 25 kg in HMH animals than in either H or L animals although, overall, the weight of TAT was greater in the H and HMH treatments than in the L treatment. A comparison of data for the H and HMH treatments showed that weight stasis decreased the weight of all separate parts of the alimentary tract, particularly the rumen-reticulum and the small intestine.Chemical analyses (water, N × 6·25 and ether extract) were conducted on four alimentary tract components, namely the combined rumen-reticulum and omasum (RRO) abomasum, small intestine and large intestine. The results of these analyses showed that composition was similar in the three treatments despite treatment effects on the weight of some parts of the tract.Chemical data were pooled across treatments to compare composition of the different alimentary tract components. This analysis showed that chemical composition was different both for all parts of the tract and for all chemical components with two exceptions. There was no difference between the RRO and small intestine for either water or ether extract.Common regression equations are presented for each component of the alimentary tract relating the weights of three chemical components to tissue weight. Water and protein content were more closely related to tissue weight than was ether extract. It is suggested that both water and protein content may show a sufficiently close relationship to tissue weight whereby they may be predicted from a knowledge of the latter, particularly the RRO and small intestine.There were no differences between treatments in the weights of fat trimmed from the alimentary tract despite treatment effects on either the weight of some parts of the tract or other offals.Apart from a greater weight of digesta in the small intestine in the H animals than in L animals relatively minor differences between treatments were found in the amounts of digesta in different parts of the tract.

Description: Evans & Roberts (1979) considered that loworder polynomials such as mean, linear and quadratic were adequate to describe the trends that occur in treatment contrasts in long-term agricultural experiments. This conclusion was based on experience with experiments on levels of fertilizers and rates of stocking on similar pastures. In such experiments, the marked seasonal pattern in the data disappears when comparisons between treatments are followed. However, further experience with experiments comparing cultivars has shown that some comparisons still show a seasonal pattern. Such patterns may be accounted for by periodic regression (Bliss, 1970).

Description: A number of attempts have been made, notably by workers in Australia (Nolan, 1975; Pilgrim et al. 1970) and Canada (Mathison & Milligan, 1971; Kennedy & Milligan, 1978a, b) to trace the metabolism of rumen ammonia-N in sheep.

Description: SummaryTwenty-five winter wheat varieties and breeders' lines including hard and soft texture, good or poor bread and biscuit-making types were grown at two locations in the U.K. in 1977 to provide the test samples. Small-scale tests of bread-making quality including extensometer, sodium dodecyl sulphate (SDS) sedimentation volume, residue protein, urea dispersible protein and Pelshenke tests, were compared with loaf volumes and loaf scores.Averaged over the two sites, a modified extensometer test and the SDS test gave the closest correlation with loaf volume and loaf score and were only poorly correlated with Hagberg Falling Number and percentage protein. The SDS test gave the closest correlation between sites followed by the extensometer readings; loaf volume and score had much lower values. The SDS values and extensometer readings give a better measure of the genetic differences in protein quality of varieties than loaf volume and score, being less affected by growing conditions. With its small sample size and high throughput, the SDS sedimentation volume is likely to be the most useful screening test for wheat breeding programmes.

Description: The solitary larval parasite Microplitis rufiventris Kok was recorded for the first time in Egypt by El-Minshawy (1963), parasitizing the lesser cotton leafworm, Spodoptera exigua Hbn. Since it could be an effective summer parasite of the cotton leaf-worm, Spodoptera littoralis Boisd., studies on aspects of its biology by Hegazi (1976), and Hegazi, Hammad & El-Minshawy (1977) have been extended to include the effect of temperature on its development.

Description: SUMMARYAn experiment at Rothamsted during 1958–67 measured effects on yield, on K uptake and on soil K of applying all combinations of 38, 75 and 113 kg N and 0, 31 and 62 kg K/ha per cut to grass leys, which were cut and removed. Soil K was depleted most where most N and least K were given. Annual applications of 0, 33 and 66 kg P/ha were also tested; soil P was not depleted. The grass was then ploughed.In 1968, residual effects were measured by spring wheat. In 1969 and in 1970 104 kg/ha of fresh K was applied on half of each plot; potatoes (1969) and spring wheat (1970) valued residual and fresh effects of K.In 1971 potatoes tested 0, 104 and 208 kg/ha of fresh K, cumulatively with the three amounts given to the grass and also extra K (104 kg/ha) on half-plots, cumulatively with that given in 1969 and 1970. In 1972 winter wheat, and in 1974 and 1975 spring barley, measured residues of all treatments previously applied (the site was fallowed in 1973).Finally, in 1976, potatoes tested 0, 156 and 312 kg/ha of fresh K on whole plots, cumulatively with the previous dressings of K, and also 156 kg/ha of extra K on half-plots, again cumulatively. All these test crops were given basal N.Yields and K contents of wheat at ear emergence and yields of wheat grain were largest after grass given 38 kg N and 62 kg K/ha per cut, because here soil K depletion was least. Wheat grain yields benefited consistently from fresh K. K content of the wheat at ear emergence was a good indicator of the need for K, but K content of grain was not, because it was unaltered by K fertilizer. Barley was a poor test crop for K, because yields of grain were little affected by previous treatments.Percentage K in potato leaves (in July in 1969 and 1971, in August in 1976) and yield of tubers were well correlated. Largest yields in 1969, 1971 and 1976 came where the leaves contained 3·43, 3·76 and 2·82% K, respectively, i.e. from soil containing most exchangeable K, plus most fresh K. There was no indication that maximum yields had been obtained, so the largest amounts (kg/ha) of fresh K tested (104 in 1969, 312 in 1971 and 468 in 1976) were insufficient to counteract depletion of soil K by the grass. Because the grass did not deplete soil P, the test crops benefited only little from either residual or fresh P.

Description: SUMMARYIn three pot experiments and one field trial, the apical portion of the main stem of two soya-bean varieties (cv. Hampton and cv. Bossier) were removed at 3 weeks or 5 weeks after sowing in order to evaluate the response of the plants to the loss of apical dominance.The results showed that early loss of apical dominance in Hampton (an indeterminate variety) led to increased vegetative development but shorter plants, higher dry-matter accumulation and increased seed yield through the production of more and/or heavier pods. On the other hand, apical debudding of Bossier (a determinate variety) during the vegetative stage evoked no significant beneficial response and in the case of field debudding at 3 weeks after sowing, plant height was decreased and seed yield was significantly reduced.The response of soya bean to the loss of apical dominance therefore seems to be a function of the stage of vegetative development when the loss occurs as well as the growth habit of the variety.

Description: SUMMARYA model study of light absorption by rectangular hedgerows with different row orientations was made.The effect of row orientation on daily light absorption is greatest around 25° latitude. North–south orientation gives highest absorption for most of the year near the equator. At higher latitudes, up to 55°, absorption is highest with N–S orientation during the summer months and with E–W orientations for the rest of the year, but the magnitude of the difference between orientations decreases with increasing latitude. From 65° upwards, E–W orientation gives highest absorption all the year round, but the difference among orientations is minor. The effect of orientation will be smaller as cloudiness is greater.The results of this study are wholly consistent with yield differences due to different orientations, reported in the literature.