The body composition of 18 each of Mashona, Afrikaner and Hereford heifers was measured at the beginning and after 16 and 32 weeks of the experiment. The heifers not slaughtered at the beginning of the experiment were fed a complete diet containing 132 g crude protein and 12·0 MJ metabolizable energy/kg dry matter. Before slaughter, the animals were deprived of food and water for 24 h. Each animal was infused with 1 mCi of tritiated water (TOH) in order to measure total body water (TBW) and to estimate body fat.

The growth rate of the three breeds of heifers was similar despite differences in age and initial live weight. Both TBW and fat proportions, however, differed significantly (P < 0·01) between slaughter stages for each breed and between breeds at each slaughter stage. At the first, second and final slaughter stages the proportions of TBW were: 68·0, 59·4 and 54·5% for Mashona; 70·;5, 64·3 and 58·3% for Afrikaner and 65·3, 57·6 and 46·2% for Hereford heifers respectively. The corresponding proportions of body fat were: 10·2, 18·4 and 24·2% for Mashona; 6·6, 12·0 and 20·0% for Afrikaner and 13·7, 20·8 and 25·8% for Hereford heifers respectively.

There was a close relation between empty body weight and live weight at slaughter which was not influenced by breed. Both TBW and fat were estimated more accurately when TOH space and live weight were used jointly. However, the slopes of the prediction equations for each breed were significantly different (P < 0·05) in the case of both total body water and fat. It was necessary to use separate equations for each breed in order to predict either body water or fat. The significance of these findings for the estimation of body fat in live cattle is discussed.

The activities of glutamine synthetase, phosphate-dependent glutaminase, phosphate-independent glutaminase, glutamate dehydrogenase, γ-glutamyl transferase and glutamine-oxo-acid aminotransferase were assayed in liver, kidney cortex, brain (cerebral hemispheres), spleen, skeletal muscle and ileum obtained from lambs of 100–260 days conceptual age. A curve was fitted to each set of data relating enzyme activity and conceptual age.

In the ileum, glutaminase and γ-glutamyl transferase activities declined during development. Glutamine synthetase activity in the spleen increased markedly after birth, whereas glutamate dehydrogenase activity declined as rumen function was established. In the liver, glutamate dehydrogenase and glutamine synthetase activities were highest in suckling lambs and there was a gradual increase in hepatic γ-glutamyl transferase activity throughout the period studied. The activity of phosphate-dependent glutaminase was lowest in the kidney cortex of ruminating lambs but renal activities of glutamate dehydrogenase, phosphate-independent glutaminase, glutamine synthetase and γ-glutamyl transferase were highest in ruminating lambs. In skeletal muscle, a gradual increase in glutamine synthetase activity occurred after 180 days conceptual age, whereas there was no detectable glutaminase activity in ruminating lambs. In the brain, there was an increase in glutamate dehydrogenase, phosphatedependent glutaminase and glutamine synthetase activities during the foetal and early suckling periods, whereas γ-glutamyl transferase activity increased throughout the period studied.

Glutamine-oxo-acid aminotransferase activity was not detected in any of the tissues studied. Phosphate-independent glutaminase activity was always less than 10% of phosphate-dependent glutaminase activity and therefore must have a minor role in the metabolism of glutamine in lambs.

A consideration of the relative activities of the enzymes at different stages of development indicated that the ileum, spleen, liver, kidney cortex and brain have a substantial potential for glutamine utilization during foetal life. As a lamb matures after birth, there are changes in the metabolism of glutamate and glutamine which indicate that there is a greater potential for net glutamine synthesis in older lambs. This could be associated with the need for detoxification of ammonia in ruminating lambs.

The 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.

Yield calibration of soil tests in western Nigeria savannah has been difficult owing to low response to P and response to only low P rates despite low available P in the soils. A study on the distribution of P forms in 60 surface soils of the savannah derived from igneous and metamorphic rocks and grouped into 11 classes was made. Average total P was 0·018% and organic P, which varied between 44 and 114 mg/kg, constituted 41% of total P. Active P components made up 40% of total inorganic P, the bulk of which was in the Fe-P fraction. All P forms except non-extractable P correlated significantly with organic matter.

The amounts of P needed to increase available P by 1 mg/kg in the soils, an index of P fixation, was correlated with pH and the free oxides of Fe and Al. The direct role of Fe-oxides and probable indirect effect of organic matter were indicated by regression analysis.

There was minimal maize yield response to P application and this was obtained only at low P rates from which an optimum rate of 20 kg P/ha was suggested. An attempt to use phosphorus sorption capacity (PSC) for P recommendation was not successful probably because of the low PSC values. A quick P recommendation based on available P status, fertilizer factor of 3·0 mg/1 and an optimum available P level derived from the relative yield v. soil P calibration curve was therefore suggested.

Growth and development of young mammals have been investigated in relation to environmental temperature and energy intake. The experimental design and statistical analysis have allowed an evaluation of the separate and combined effects of two environmental variables and the time it takes for these effects to develop. Piglets aged 14 days lived at either 35 or 10 °C, on a high or low energy intake (the energy content of the former was twice that of the latter). The influence of each of the four treatment combinations was assessed up to 64 days of age.

At 64 days of age the piglets at 35 °C on the high intake (35H) were twice as heavy as those at 10 °C on the low intake (10L). The other two groups (35L and 10H) had similar body weights, and these were between the 35H and 10L. Ambient temperature had a rapid influence on appearance and morphology: animals in the cold were shorter and squatter than those in the warm. In general, energy intake influenced the absolute size of the internal organs whereas temperature affected their size relative to body weight. Skeletal growth was faster in the warm than the cold, and on the high than the low intake. No statistically significant interactions were generally found between temperature and intake, indicating that their effects were exerted independently. Most of the effects were established after only 17 days.

The present investigation has helped in interpreting earlier studies on growth which concentrated on the effects of only one of the two environmental variables of temperature and nutrition. It emphasizes the key roles of nutrition in adaptation to environmental temperature, and of ambient temperature to nutritional studies.

The grain weights of normal and high-lysine cultivars were compared in field and pot experiments in which the supply of assimilate per grain was adjusted by a variety of treatments involving application of fertilizer, thinning, degraining or defoliation. The results of these experiments indicated that in normal cultivars, grain weight was affected both by the supply of assimilate from the green tissues and by internal factors in the grain which limited the accumulation of this assimilate. Some evidence suggested that physical constriction of the expanding endosperm by the surrounding husk could be one of these factors; the effects of the husk on growth of the caryopsis was not clear.

The development of grain weight in the high lysine cv. Riso 1508 was initially similar to that of normal cultivars, but the cessation of growth as maturity approached was more abrupt. Increased assimilate availability resulting from the application of fertilizer, thinning or degraining treatments effectively increased grain weight in this cultivar, but to a lesser extent than in low-lysine cultivars. Conversely, decreased assimilate supply as a result of defoliation produced less marked reductions in grain weight in the high-lysine type, suggesting that the reduced starch accumulation associated with the high lysine characteristic rendered superfluous some of the photosynthetic capacity in these types.

Field experiments on the effect of moisture regimes and fertilizer application on fibre yield of two jute varieties showed that JRO 632 (Corchorus olitorius L.) produced significantly more fibre, utilized moisture more efficiently and extracted water from deeper layers than did JRC 212 (Corchorus capsularis L.). Scheduling of irrigation at 20% available soil moisture (ASM) gave the highest fibre yield in normal (1970) and drought (1972) years but unirrigated conditions (dry regime) gave highest yield in a year of excess rainfall (1971). The consumptive use (CU) increased from dry to wet regimes and the water use efficiency (WTJE) was greater in dry regimes in normal as well as in excess rainfall years. But the WUE was maximal when the crop was irrigated at 60% ASM in the drought year. The water requirement of the jute crop was 490 mm in the normal and excess rainfall years (20% ASM and dry regime respectively) while in the drought year it was 560 mm (20% ASM). The moisture extraction was more from deeper depths in the dry regime and only from shallower depths in wet regimes.

The fibre yield increased with increase in nitrogen application from 40 to 80 kg/ha. Application of 40 kg P2O5 and 40 kg K2O/ha did not improve the fibre yield in the excess rainfall and drought years. In the drought year (1972) irrigating at 20% ASM and 80 kg N/ha and in the excess rainfall year (1971) the dry regime with 40 kg N/ha produced highest fibre yields. There was not much variation in CU and WE of the crop due to different fertilizer levels. The WUE was increased by irrigating at 20% ASM with 80 kg N/ha in a crop rotation system where P and K were applied to preceding crop.

One 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.

Neem (Azadirachta indica juss) seed kernel cake was water treated and dried in the sun. It was palatable to cattle, despite its bitter smell.

Twelve growing calves were divided into two equal groups; one group (control) had a standard concentrate mixture consisting of crushed maize 30 parts, groundnut cake 30 parts, wheat bran 38 parts and in the second group (experimental) the concentrate mixture had crushed maize 30 parts, neem seed kernel cake (water washed) 45 parts and wheat bran 23 parts. Both the mixtures had common salt and mineral mixture 1 part each. The roughage fed was the same in both groups.

The mean growth rate of calves in 273 days was 403 g/day in the control group and 344 g/day in the experimental group which did not differ significantly (P > 0·05). The dry-matter intake, digestibilities of all the organic nutrients, total digestible nutrient values and the balances of nitrogen, calcium and phosphorus remained similar (P > 0·05) in the two groups. The blood haemoglobin, serum inorganic phosphorus and the activity of serum alkaline phosphatase, serum acid phosphatase, serum glutamic-pyruvic transaminase and serum glutamic-oxaloacetic transaminase also did not differ significantly (P > 0·05) in the two groups.

It is concluded that water washing of neem seed kernel cake very largely removes toxic principles responsible for retardation in growth.

Main-stem apical development and its inter-relations with other aspects of plant morphology were studied in seven field crops of winter wheat (Triticum aestivum L., cv. Maris Huntsman).

Apical primordia were produced slowly in autumn and winter, then faster in spring as the weather became warmer. Spikelets were initiated about three times as fast as leaves. Leaf initiation ended at around the time that tiller bud initiation stopped. Apical dome length and diameter both increased during leaf initiation, reached a maximum at double ridges and then decreased. Double ridges appeared when very nearly 50% (range 49–52%) of the final number of spikelets was present. Spikelet initiation ended a few days after the first florets were initiated and when stem extension began, but usually before the stem apex rose above the soil. Floret initiation finished at about the time that the flag leaf appeared. Throughout tillering there was a strong association between tiller emergence and leaf appearance.

There were considerable differences between seasons in the timing of developmental events on the apices of main stems, but a difference in sowing date of 5 months was reduced to little more than 1 month in the timing of anthesis and the maximum numbers of organs varied only slightly with sowing date.

A scheme was developed to describe how the rate at which apical primordia are initiated in cereals depends on temperature and photoperiod. It was used to analyse initiation in field crops of winter wheat (Triticum aestivum L., cv. Maris Huntsman).

For the initiation of leaves and spikelets, a straightforward linear regression of initiation rate R against mean air temperature (Ta) gave base temperatures (Tb) close to 0 °C for leaves and for spikelets. However, initiation rate was also correlated with mean photoperiod (P) and base photoperiods (Pb) of –0·5 h and 4h were established for leaf and spikelet initiation. When R was correlated with the index (T – Tb) (P – Pb), r2 was 0·62 for both leaves and spikelets.

Measurements were taken on 36 laying hens, 46 growing female turkeys and 36 broiler chickens using modified abdominal fat calipers to determine the prediction of abdominal fat in different classes of poultry. Four pairs of caliper measurements were taken on each bird by three operators (layers and turkeys) and one operator (broilers). The live laying hens and the plucked turkey carcasses were also scored for fatness. The caliper measurements were significantly related to the proportion of abdominal fat (g abdominal fat/kg body weight) in all three groups of birds. The correlation was greater in laying hens (0·81) and turkeys (0·76) than in broilers (0·51). There were significant operator effects upon the prediction of abdominal fat. In each case the measures obtained by two practised operators gave better prediction of abdominal fat than those from an unpractised operator.

The body composition of young mammals has been investigated in relation to environmental temperature and energy intake. Piglets were weaned at 14 days and then kept separately at 35 or 10 °C and fed either a high or a low energy intake. The animals were killed at 38, 48, 56 or 64 days of age and the carcass divided into four compartments: superficial tissue (skin and subcutaneous adipose tissue), muscle, contents of abdomen (gastro-intestinal tract, liver and kidneys), contents of thorax (heart and lungs). Each compartment was analysed for fat, nitrogen and energy content.

The results were analysed using a non-orthogonal analysis of variance in oider to investigate the separate effects of environmental temperature and energy intake, to test for possible interactions between these two factors, and to assess the time it takes for any effects to develop.

The total amount of fat stored in the body was greater in the pigs kept at the high temperature than in those kept at the low temperature and increased with an increase in food intake; there was no evidence of an interaction of temperature and diet, suggesting that their effects were exerted independently. The extra fat was stored mainly in the superficial tissue and muscle, but partly also in the deep body compartments. However, when expressed as a percentage of the total fat store a greater proportion was found in the deep body compartments of those kept at the low temperature and on the low intake, although the absolute quantities of fat involved were small.

The nitrogen content was also greater at 35 than at 10 °C, and on the high than low intake. Most of the nitrogen was present in the muscle and the proportion of the total body nitrogen stored here was greater in the warm than in the cold, whereas it was unaffected by energy intake. The energy contents of the tissues measured by bomb calorimetry and estimated from the chemical composition were similar. For animals kept at 35 °C most of the energy was stored in the superficial tissue, with the muscle as the second highest store. By contrast, those in the cold stored most of their energy in the muscle.

The present investigation has thus highlighted the large and partly independent effects that environmental temperature and food intake can have on the distribution of energy within the body and the chemical form in which it is stored.

The 65 spring and 14 winter cultivars of barley on the 1981 U.K. National List were examined electrophoretically for allozyme variants of phosphoglucoisomerase (PGI). Two different banding patterns were observed, a ‘fast’ and a ‘slow’ migrating type. With the exception of six spring cultivars in which the ‘slow’ type was found, all the cultivars were classified as ‘fast’. F2 progeny of crosses between ‘fast’ and ‘slow’ plants were used to interpret the banding patterns as resulting from the dimeric isozymes of two alleles (allozymes) each producing a triple band pattern, the faster two bands of which were considered to be ‘secondary’ or artefact bands. With the notable exception of Dragon and its sister line RPB 1115–75 all of the other ‘slow’ cultivars and breeders' selections were found to have the ‘slow’ cultivar Midas in their breeding history. Midas was bred using material from three ‘fast’ cultivars and a γ-ray mutant strain, the irradiation which produced this strain being regarded as the likely cause of the ‘slow’ isozyme. Unlike all the other cultivars tested, Midas was found to be a mixture of genotypes comprising 73% ‘slow’ and 27% ‘fast’ plants, a ratio which was most probably due to founder effects caused by the breeders' selection programme. In the light of the present investigation and other reports it is concluded that it is not an uncommon occurrence to find plants with different electrophoretic banding patterns within inbred cultivars.

This result has serious implications for cultivar registration as there is a possibility of selecting electrophoretically distinct plants from within existing registered cultivars. It is concluded therefore that the protection afforded to plant breeders under Plant Breeders' Rights schemes could be seriously threatened by the use of electrophoretic characters for cultivar registration except in some specific incidences where it may be possible to apply appropriate safeguards. The implications for plant breeders of the existence of isozymes of PGI, of possibly different efficiencies, within commercial cultivars of the genus Hordeum are also discussed.

Selections for erect-(E) and lax-leaf (L) posture in winter wheat were made from a cross between parents which contrasted in the character. By the F5 generation there were consistent, heritable differences between E and L lines. The lines were evaluated in three field experiments and a glasshouse experiment.

In an experiment in which plots were automatically sheltered from rain and in which there were three irrigation treatments, there was no treatment-posture interaction, and over all treatments E lines outyielded L lines by 0·26 t/ha. When fully irrigated the water use of both E and L lines between 1 May and maturity was approximately 280 mm. Withholding water caused a reduction in water use and a corresponding reduction in grain yield for both E and L lines.

When the four most erect- and the four most lax-leaved lines were considered over all three field experiments, E lines maintained a slight, though not significant, grain yield advantage of 0·17 t/ha over L lines. However, the E lines produced significantly more biomass, averaging 0·7 t/ha more than L lines, and this extra biomass was not produced at the expense of additional water requirement. However, results from the glasshouse experiment suggested that the E lines may be more susceptible to a substantial pre-anthesis drought.

It is concluded that varieties of winter wheat with the erect-leaf habit may provide an opportunity of increasing biomass production. In an environment in which a preanthesis drought is unlikely to occur, such varieties may give the highest yields. However, on light soils prone to early drought or at sites which would not permit the maximum expression of leaf area index at anthesis, varieties with a lax-leaf posture may give greater yield.

Rhizobium strains adapted to high temperature, and genotypes of green gram, were used to study the symbiotic N2-fixation in a summer season at two moisture levels in calcareous soil. Different interactions between strains and genotypes were observedatthe two moisture levels. At both moisture levels, strain S4 with the green gram genotype S8 showed the greatest grain yield, nitrogenase activity, leghaemoglobin and ethanolsoluble carbohydrate of nodules.

A 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.

A simple model of the mammary gland is described. In this model secretory cells are produced by cell division from undifferentiated cells, and the rate of division is determined by the level of a postulated hormone. The total activity of the milk secreting cells depends on the number of cells, substrate supply (assumed constant), and the amount of milk currently present in the animal. The secretory cells have a finite life, although their death may be expedited by milk remaining in the animal over a longer period of time. The model gives a good description of an experimental lactation curve; it is able to simulate the removal of milk by a suckling calf and machine milking with a variable number of milking periods a day.

The results of experiments conducted for 2 years in north-western India under irrigated conditions are described here. Wheat following legume intercrops gave increases in growth, yield attributes, yield and N uptake. Various legume intercrops such as groundnut, cow peas (both for fodder and grain) and greengram reduced the need of fertilizer nitrogen for wheat in the succeeding season by 30–84 kg/ha compared with sorghum.

In 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.