Individual muscles, individual bones and fat depots from the non-carcass parts (head, foreshanks and tail) of 40 steers (chilled carcass weight 142–174 kg) were studied in an attempt to predict carcass composition more accurately than in an earlier study where the crude non-carcass parts, head, tongue, foreshanks and hindshanks were used.

The technique did not improve the accuracy of prediction of muscle or bone. Carcass fat, which was calculated by difference in the earlier study, was predicted more accurately using intermandibular fat weight (requiring 3–4 min to obtain) plus fat thickness at the 12th rib. However, the accuracy of this prediction (carcass fatness range 14·0–33·6%, residual standard deviation 1·98%) was no greater than that using chilled side weight plus fat thickness at the 12th rib.

Careful dissection and trimming of anatomical entities from the non-carcass parts therefore offered a slight advantage only in the prediction of carcass components over existing techniques.

Substitution of hot side weight for chilled side weight, and sacral crest fat thickness for fat thickness at the 12th rib did not lead to a loss in the accuracy of prediction of muscle, bone or fat.

Two digestion trials were performed with sheep in order to assess the effect of the sulphur dioxide treatment on the digestibility of wheat straw in vivo. In the first trial, untreated and SO2-treated straw served as the major components of the diets. Sulphur dioxide partly solubilized the cell wall (CW) material of the straw, decreasing its content from 78·5 to 55·9%. The digestibility of the residual CW was increased from 49·2 to 77·8%, whereas the digestibility values of the cell-soluble fraction (CS) were unaffected by the treatment: 55·8 and 57·8% for the untreated and treated straw, respectively. Apparent digestibility of the organic matter (OM) was increased by the treatment from 46 to 65%.

In the second trial SO2-treated wheat straw was fed together with concentrates at a D.M. ratio of 30/70, and the digestibility of the OM and CW was determined.

CW and OM digestibilities of the treated straw were not affected by 70% concentrate in the diet and the respective values were 77·0 and 65·5%, very similar to those found in the first trial. The reason for the in vitro–in vivo discrepancy is discussed.

Azospirillum brasilense was treated with nitrosoguanidine and five drug-resistant mutant strains isolated. The effects of acriflavin on pre- and post-irradiation with u.v. light and the level of antibiotic resistance were studied. Variations in factors were found between the strains. Inoculation of finger millet with A. brasilense and mutant strains led to significant increases in grain yield and nitrogenase activity compared with the uninoculated control, with significant strain x genotype interactions. Differential response of genotype and strain was noted on the protein and amino acid concentration of seeds.

The analysis of plant competition experiments in which all possible pairs of p genotypes are grown in replacement series is discussed. Two methods of analyses, using models of de Wit (1960) and Gleeson & McGilchrist (1980), are compared. The two approaches, which are shown to be linked algebraically, complement each other in terms of agronomic interpretation.

A replicated, long-term field drainage experiment on a clay soil was started in 1978 to investigate the effects of mole drainage on land that had been direct-drilled or ploughed. We here describe the background and the need for this work, details of the experiment and summarize the results for the first 2 years. The main factors causing point-to-point variability in the soil at the experimental site and their relative contributions were assessed. Variations in inherent soil properties were small, except for depth to calcareous clay. Site hydrology was also generally uniform, especially soil water content, and was little affected by the presence of subsoil drainage schemes dating from the 19th century. There were some variations in micro-relief. The drained and undrained plots were hydrologically separated. Equipment was installed to measure separately surface runoff, lateral flow at the bottom of the cultivated layer (the interflow) and deep drainage from the mole and pipe system (in the drained plots only). The design and performance of that equipment is described. In both years much of the undrained soil became saturated in winter, but a residual cultivation pan limited the effect of the mole drains in 1978–9. In 1979–80, after disrupting the pan, the water table in the moledrained plots was about 25 cm deeper than in the undrained plots, root growth was greater and yield of winter wheat 11% heavier. About 90% of water and nutrients draining from the drained plots were carried in the mole and pipe system. The results on water balance, nutrient losses, crop growth and yield are fully reported in companion papers (Harris et al. 1984; Ellis et al. 1984).

The soil water regimes, flow paths of water and concentrations of nutrients in this water were measured for a clay soil growing winter wheat in 1978–9 and 1979–80. The soil was either drained with mole drains at 2 m spacing connected to plot drains 46 m apart or undrained. In the 1st year a compacted layer at about 20 cm depth caused a perched water table in the Ap horizon in both drainage treatments, and prevented the mole drains at 60 cm from affecting the water table. In 1979–80 after cultivation to disrupt the compacted layer, midway between the mole drains the depth to the winter water table was 20 cm greater than in undrained soil.

Surface flow, interflow at the depth of the plough layer and deep drainflow from mole and pipe drains responded rapidly to winter rainfall events. During both winters the mole and tile system removed most of the rainfall on the drained plots and the peaky hydrographs were typical of a mole system in a clay soil. In the undrained plots only a small proportion of the winter rainfall was accounted for in flow from the top 30 cm, and up to 75% of the water was able to percolate downwards possibly to below the barriers that separated the plots. Long-term water-balance studies indicated that a proportion of the water moving to depth in the undrained plots was probably entering the deep drainage system of the drained plots. As a result, the mole and pipe drainage system often removed more water than the rainfall input less evapotranspiration. This problem did not affect the depth to the water tables.

For each flow component concentrations of nitrate, ammonium, nitrous oxide, phosphorus, potassium and calcium were measured in the drainage water. Concentrations of nitrate-N from all drained plots were largest in autumn, being in the range 50–95 mg N/1, but then decreased to 1–5 mg N/1 by the end of March. Losses of nitrate-N were mainly through the mole drains and amounted to 43·6 and 59·7 kg N/ha in the 2 years. The quantities of nitrate-N lost in surface runoff or in flow in the cultivated layer were small on both treatments. Gaseous nitrous oxide, ammonium and phosphorus contents were very small. Potassium concentrations were somewhat larger, but not exceeding 3·5 mg/1. The calcium concentrations were in the range 40–210 mg/1. Concentrations of herbicides measured in November 1980 were negligible.

In the 2nd year water was taken up from a greater depth in the drained than in the undrained plots from April onwards. These results are discussed in relation to water supply to the crops at this site.

Grain yield of winter barley in the year preceding the experiment (1978) was relatively uniform over the site. In 1978–9 after the drainage treatments had been introduced, growth and yield of winter wheat were not affected by drainage, probably due to a compact layer at 20 cm that prevented the mole drains from controlling the water table (Harris et al. 1984).

In 1979–80 after disrupting this layer, root growth in undrained plots during the winter and spring was severely restricted by the presence of a water table 20 cm from the soil surface, although some root axes were able to grow down to 75–100 cm below the soil surface. The differences in root distribution patterns between drained and undrained plots disappeared after the water table declined in April. Uptake of nitrogen, phosphorus and potassium were less on undrained plots. Dry-matter production, leaf area index and peak number of tillers was also depressed, so that the yield of winter wheat was 0·74 t/ha greater on the drained treatment; the grain from the drained plots contained fewer impurities and weed seeds.

A missing value technique for the analysis of data where repeated measurements are taken on each experimental unit is proposed. The method suggested, which is a natural multivariate analogue of the well-known technique for univariate analyses, fits those missing values which minimize the determinant of the sums of squares and products matrix and provides the necessary downward adjustment to the residual degrees of freedom. A simulation exercise provides evidence that the method is fairly reliable.

Calcium metabolism in dairy sheep was studied using radioisotope and balance techniques. The rate of calcium absorption increased, but the efficiency of calcium absorption decreased, with increasing calcium intake in dry sheep. Endogenous faecal and urinary calcium losses, and the rate of calcium absorption, decreased, but the efficiency of calcium absorption increased in pregnant sheep given a calcium-deficient diet. The rate and the efficiency of calcium absorption and the calcium balance of lactating ewes were not influenced by the prepartum level of calcium intake, when calcium intake in early lactation was high. Endogenous faecal calcium loss was related to dry-matter intake, and total faecal calcium loss was related to calcium intake.

The effects of including monensin in the diet on the dynamics of protozoa in the rumen of sheep were investigated using injections of protozoa labelled with 14C-choline.

The half time of rumen fluid was higher in sheep receiving monensin but neither the pool size nor the composition of protozoa species (mainly smaller entodiniomorph ciliates) was significantly affected.

More protozoa passed out of the rumen as liquid outflow rate increased and there was a tendency for the apparent production rate of protozoa to be higher with the resulting increase in washout of protozoa.

Various population improvement methods were applied to the spring-sown bulb onion crop. Synthetic populations were developed by recurrent selection, basing this selection on the performance of inbred lines per se for improved yield, bulb quality and storage performance. From the synthetic populations, partially inbred populations were also developed by half-sib selection methods. Results showed that gains, primarily in storage performance and marketable yield, were obtained in many of the synthetics. The mean gain in yield per cycle was of a similar magnitude to gains reported for maize using similar selection procedures although individual onion synthetic populations varied considerably in their achieved gains. Further gains in quality and storage performance, with no reduction in yield, were obtained by the development of partially inbred populations from the synthetics. These results are discussed in relation to the breeding of improved onion cultivars in the U.K.

The relationship between structure and the ability of piglet intestine to transport alanine has been determined during the first few weeks of postnatal life.

Villus length halved without change in crypt depth during the 3rd week of postnatal life. A similar shortening of villi, accompanied by an increase in crypt depth, took place when 2-week-old piglets were weaned on to a solid diet. Weaning piglets at 3 weeks increased crypt depth without causing further shortening of villi.

Alanine transport was shown, by quantitative autoradiography, to be largely confined to enterocytes in the region of the villus tip. The way in which this transport function developed was analysed further by fitting logistic growth curves to measurements of intra-enterocyte alanine concentration. The ability of enterocytes to transport alanine occurred earlier and alanine was accumulated to higher concentrations in enterocytes studied in 21- compared with 15-day-old unweaned piglets. Weaning piglets on day15 or 21 and measuring alanine transport 5 days later produced a pattern of development similar to that reported previously for adult animals.

Transport of alanine throughout postnatal development showed sodium dependency. Effects of alanine on intestinal short-circuit current of weaned piglets were again similar to those recorded in adult animals.

These results are discussed in terms of intestinal adaptation to a changing environment and in relation to the ‘notional capacity’ of a pig villus to transport amino acids during the early postnatal period of development.

Kale of normal and low S-methyl-L-cysteine sulphoxide (SMCO) content was produced by growing the same cultivar in soils of normal (20–30 mg/kg) and low (5–10 mg/ kg) soil sulphate-S concentration. Compared with normal S plots, kale grown in low S plots showed little or no reduction in D.M. yield or total N content, but contained lower concentrations of inorganic sulphate, SMCO and glucosinolates.

Replicated plots of normal and low SMCO kale were grazed by lambs for 12-week periods in two consecutive years, using a fixed crop allowance of 2·5 kg D.M./animal/ day. All animals were given injections of copper and iodine, and oral supplements of selenium, to ensure that effects upon animal performance could largely be attributed to differences in kale SMCO concentration.

SMCO concentration in the diet consumed by lambs grazing normal and low SMCO kale was respectively 0·60 and 0·35% D.M. Following the onset of kale feeding, all animals developed subclinical haemolytic anaemia which stabilized by week 6, and was more marked during weeks 1–6 than during weeks 7–12. Animals grazing low SMCO kale showed a less severe anaemia than those grazing normal SMCO kale, which was associated with lower blood concentrations of dimethyl disulphide and Heinz bodies, and higher reduced glutathione (GSH) and packed cell volume (PCV) levels. Liveweight gain and wool growth were greater for lambs grazing low than normal SMCO kale during weeks 1–6, corresponding to the period of most severe haemolytic anaemia, but during weeks 7–12 there were no differences between the two groups.

It was concluded that SMCO content depressed kale feeding value, with most of the depression occurring in the first 6 weeks of grazing, and that in these experiments the lambs were able to adapt to kale containing 0·6% D.M. as SMCO after 6 weeks of feeding. Endocrine factors involved in this adaptation are discussed.

Chaffed lucerne hay of 64% apparent organic matter (OM) digestibility was fed to wether sheep under four feeding regimens: two levels of dry matter (D.M.) intake (700 (L) and 1050 (H) g/day) and within each level two feeding frequencies (once a day (daily) and once an hour (hourly)). Three separate groups of sheep were used concurrently: a slaughter group was used to obtain feeding behaviour data and to measure pool sizes and obtain samples from the reticulo-rumen; a digestion group, in which each sheep was prepared with a rumen and a duodenal cannula, was used to measure duodenal digesta flow, rumen microbial growth and reticulo-rumen motility; a balance group was used to measure digestibility and nutrient balances.

High D.M. intake increased reticulo-rumen pool sizes and flow rates but it did not affect apparent digestibilities or the proportions of OM, fibre, cellulose, hemicellulose, lipid and nitrogen digested in the stomach and intestines. Increased feeding frequency had a major effect on reticulo-rumen pool sizes but did not affect apparent digestibilities or partition of digestion of non-nitrogenous constituents. Daily feeding resulted in increased total-N flow to the duodenum; however, N retention was significantly greater with frequent feeding. It is suggested that this was due to a more efficient tissue utilization of N.

The kinetics of digesta flow within the reticulo-rumen, expressed as fractional flow rates, were studied with data from sheep fed hourly. The fractional inflow, outflow and disappearance rates for OM, fibre, cellulose and hemicellulose did not change with an increase in intake because of an equivalent increase in reticulo-rumen volume. Increasing D.M. intake by 50% resulted in a 24% increase in water intake, a 19% increase in reticulo-rumen water volume, and a 49% increase in water outflow rate. The data suggest that the increased outflow of water was achieved by increasing the net flow of water across the mucosa into the reticulo-rumen, rather than by increasing salivation.

There was no difference between treatments in the frequency of reticulo-rumen contractions. It was calculated that for each A sequence contraction, OM flow was 0·26 and 0·37 g and water flow was 4·38 and 0·36 g on L and H intakes respectively. A 50% increase in intake resulted in a 42% increase in OM passage per A sequence contraction. This increased passage with intake was not accompanied by an increase in reticulorumen contraction frequency.

Seven out of ten chemical extractants were found to be promising for the evaluation of critical limit and response of wheat grown in pots to Cu application in Sub-Himalayan hill and forest soils of recent alluvium origin. The critical limit of available Cu using DTPA-CaCl2(pH 7·3), DTPA-NH4HCO3 (pH 7·6), EDTA-(NH4)2CO3 of pH 8·6, EDTANH4OAc (pH 7·0), n-NH4OAC (pH 7·0), n-NH4OAC (pH 4·8) and n-Mg(NO3)2 of pH 5·9, was 0·66, 1·73, 1·95, 1·38, 0·13, 0·20 and 0·47 mg Cu/kg, respectively. The amount of Cu extracted by these extractants was positively and significantly correlated with ‘Bray's percent yield’. Apart from ‘Bray's per cent yield’, the Cu extracted by most of these extractants was positively and significantly correlated with Cu concentration in the third leaf of wheat, Cu uptake by wheat shoots and organic carbon content of the soils, and negatively correlated with soil pH but the value of this relationship did not approach the 5% level of significance. n-Mg(NO3)2 of pH6·7, N-NH4NO3 and 0·1 n-HCl were found to be ineffective extractants. Among chelating agents, DTPA-CaCl2 was found to be most and EDTA-NH4OAc least promising extractant. N-NH4OAC (pH 4·8) proved to be better than N-NH4OAC (pH 7·0). The critical Cu concentration in the third leaf of wheat was 8·8 mg Cu/kg, below which responses in dry weight to Cu application may be expected.

Changes in distribution of amino acid nitrogen of chopped wheat plants ensiled at shooting and flowering when wilted, and at the milk and dough stages as fresh material, were determined as affected by addition of 0·8% propionic acid (PrA) or 2·2% urea phosphate-calcium propionate (UP-CaPr). Analyses were carried out after an ensiling period of 90 days and after a further aerobic exposure period (AE) of 7 days.

Total amino acid (TAA) contents in the dry matter (D.M.) during the fermentation period and in the AE were stable in untreated material (UM) and treated material. Concentration of essential amino acids decreased during fermentation, this decrease being higher in the UM. The free amino acids were low in the fresh material (18·6% of TAA) but increased in the ensiled material to ca. 71 % of the TAA in the silage. In the AE this level was 63% in UM and 69% in treated material. The ammonia-N contents increased during fermentation in UM and especially in the UP-CaPr treatments, while the opposite occurred in the PrA treatments.

The concentrations of and changes in 21 amino acids (AAs) are given. The highest AA concentrations recorded in the fresh material were those of arginine, lysine, glutamic acid, alanine, leucine, proline and glycine. The most marked increments in AAs as a result of fermentation were those of ornithine, γ-amino butyric acid, threonine and methionine. Marked decreases were observed in glutamine, arginine and glutamic acid. PrA increased mainly arginine, asparagine and glutamine, whereas γ-amino butyric acid decreased; UP-CaPr increased arginine, asparagine, lysine and glutamic acid (in silage only) and reduced γ-amino butyric acid and glutamine (in AE only).

Three experiments were carried out in which nitrogen was applied to spring barley (cv. Midas) either all in the seed bed or as a divided dressing with 10 or 25 kg/ha in the seed bed and 50 or 60 kg applied at emergence or 10, 20, 30, 40, 50, 60 or 70 days after emergence. Applying part of the nitrogen as a top dressing up to 30 days after emergence and 50 days after emergence had no significant effects on the grain and straw yields respectively, compared with applying all the nitrogen in the seed bed. Grain yields were progressively reduced with top dressings from 40 days after emergence (first node stage) onwards. Applications at 60 or 70 days did not give more grain yield than the no-nitrogen control, but gave straw yields which were intermediate between the no-nitrogen and seed-bed nitrogen treatments. Top dressing at 40 days after emergence stimulated tiller survival but did not improve grain yield because there were fewer grains per ear. Thousand-grain weights were lowest with top dressings at 50 days after emergence and grain nitrogen increased progressively with delay in top dressings from 30 days after emergence onwards.

Experiments using intact seedlings and detached leaves failed to confirm previous reports that ammonia gas is evolved from barley leaves during the establishment of infection by the powdery mildew fungus Erysiphe graminis f.sp. hordei.

In the experiments using intact seedlings infection did, however, lead to greater concentrations of ammonium nitrogen in the senescing leaves and, in one experiment, the subsequent evolution of ammonia gas from these seedlings. Losses of nitrogen as ammonia gas from crops are probably small, but it is possible that under some circumstances they may represent a significant proportion of the otherwise unexplained nitrogen losses and hence be important in experiments which aim to study the nitrogen balance of crop-soil systems.

If atmospheric carbon dioxide concentration continues to increase, plant growth and crop yield could be affected. New Yorker and Better Boy cultivars of tomato (Lycopersicon esculentum) were used to investigate possible intraspecific variation in the response of crop species to increased CO2. Because precipitation and temperature are predicted to change with the increasing atmospheric CO2 concentration, the response of the two cultivars to the interaction between CO2 and water stress was also examined. Seeds of the two cultivars were germinated and grown under controlled environmental conditions, in either 350 or 675 μ1 CO2/1.

The plant water status of the two cultivars was inherently different but was little affected by the CO2 concentration when the plants were well watered. When water was withheld for 5 days the total leaf water potential and osmotic potential decreased in both CO2 treatments but less rapidly in high CO2 than in low. Under low CO2 total leaf water potential decreased to a lower value than osmotic potential. The differences were due, at least in part, to the reduced stomatal conductance and transpiration rate under high CO2.

Increased CO2 ameliorated the detrimental effects of drought stress on plant growth. The results indicate that increased CO2 could differentially affect the relative drought resistance of species cultivars.

Grass silage was incubated in polyester bags in the rumens of Jersey heifers for 2, 12, 24 and 48 h. The total (D + L) and D-amino acid contents of the silage and of the silage residues remaining after rumen incubation were determined. In addition, the contamination of the silage residues by rumen bacterial protein was measured by using 35S as a marker of rumen bacterial protein. The amino acid profile of the residual silage dry matter differed markedly after 2 h of rumen incubation from that of the original silage; thereafter progressive changes in the amino acid composition of the residual silage dry matter occurred between 2 and 48 h of rumen incubation. The D-alanine content of the original silage was higher than that of D-glutamic acid. Both these D-amino acids disappeared almost completely from the silage after 2 h rumen incubation; between 2 and 48 h rumen incubation the quantities of D-alanine and D-glutamic acid in the residual silage dry matter increased. The residual silage dry matter contained more D-glutamic acid than D-alanine and these acids were in a similar proportion to that found in rumen bacteria; thus it was concluded that D-amino acids in the residual silage dry matter resulted from contamination of the residues by rumen bacteria. Contamination of residual silage protein by rumen bacterial protein increased with length of rumen incubation; the extent of contamination was similar for each incubation time whether assessed using 35S or D-amino acids as markers of rumen bacterial protein. However, this contamination by rumen bacterial protein did not markedly alter the degradability of silage protein calculated from the disappearance of silage N incubated in sacco.