There have been considerable changes during the last ten years in the ways in which agricultural research is organized in many countries. These changes are of interest to our readers and for this reason the Editors have invited the Agricultural and Food Research Council of the United Kingdom to explain present structures within that organization. The Agricultural and Food Research Council receives funds for research directly from the Department of Education and Science (c. £54 million per year) and through commissions from the Ministry of Agriculture, Fisheries and Food (c. £44 million) as well as from commercial and other organizations (c. £13 million). It advises the Department of Agriculture and Fisheries for Scotland, which is the body responsible for the Scottish agricultural research institutes (spending c. £22 million per year), on scientific aspects of the research they finance and also provides support to universities and other educational establishments for the support of scientific studies relevant to agriculture and food.

The effect of moisture stress on N fertilizer needs of spring wheat (Triticum aestivum L.) was assessed using yield and meteorological data from N x P and N x P x K factorial trials, conducted on farmers' fields in a summer and a winter rainfall area in South Africa in 1979–84. Three to five rates of N fertilizer between 15 and 135 kg N/ha (plus control) and two to four replicates were used. The data were statistically analysed by a multiple regression yield model using applied N rate, N, and seasonal moisture stress, S, as the explanatory variables. A good positive correlation (r = 0.83, S.E. = 0.341 t/ha, D.F. = 48) was obtained between the estimated and the observed yields. The effects of S on Nmax and Novl (i.e. the N rates corresponding to maximum yield and an economically optimal rate, respectively), were evaluated. For 0.05 < S 7lt; 0.3, the range of S values representative of dryland cropping conditions, Nmax was largely independent of S, whereas Nopl increased sharply with decreasing S. The results indicated that N-response models which include moisture stress parameters may be used to determine the cropping areas climatically most suitable for wheat cultivation.

Ten selections from the cultivar China A, with widely different pod lengths, were compared in a single environment in Perth in 1983. Pod length was correlated positively with seed weight per pod but negatively with number of pods per plant. As a result, there was no significant relationship between pod length and seed yield, although the highest- and lowest-yielding lines were, respectively, longand short-podded.

Two lines differing markedly in pod length were compared in a second experiment in 1984 in which sowing date and plant population density within a sowing date were varied. Although pod length was relatively stable, seed yield and some of its components were greatly affected by sowing date and plant density. Again, the long-podded line produced fewer pods with a greater weight of seed per pod than the short-podded line in most conditions. Compensation for greater seed weight per pod by a reduction in number of pods per plant was primarily responsible for the absence of significant differences in yield between lines in any treatment.

Although long pods generally produced a greater weight of seeds per pod than short pods, the advantage in seed number and/or the weights of individual seeds was less than that expected pro rata for the much greater pod length. Indeed, short pods produced more seeds per unit length of pod than long pods. This suggested a less efficient distribution of assimilates within the longer pods, a greater amount being required to support the growth of pod walls than in short pods.

Alternative approaches to using pod length as a criterion of selection for high yield are discussed.

Estimates were made of the dry matter (DM) yield and N content of cereal grains harvested from trial plots. They included 236 combinations of variety and treatment, with 13 varieties of winter wheat grown under six husbandry regimes, 14 varieties of spring barley under three husbandry regimes and ten varieties of winter barley under 11 husbandry regimes. The husbandry included timing and rate of fertilizer application, use of growth regulator and fungicide, and seed rate.

For all three cereals, there were highly significant positive associations between grain N content (g/kg DM) and grain DM yield (t/ha) when individual varieties were grown under different conditions. The regression coefficients were: winter wheat 2·28, spring barley 0·74 and winter barley 1·06. When varieties were compared under constant husbandry, the association between N content and yield was negative; the regression coefficients were: winter wheat – 1·53, spring barley –1·14 and winter barley –1·21.

The contents of lysine, threonine, isoleucine and valine were examined in 19 samples of winter wheat, 19 of spring barley and 21 of winter barley. Each cereal type included a comparison of varieties under one husbandry regime and a comparison of husbandry regimes in one variety.

The amino acid composition of wheat protein changed little with either variety or treatment. In spring and winter barley, lysine concentration in grain protein (g/16 g N) decreased with increases in grain N which arose from additional fertilizer N. There were similar decreases in threonine, isoleucine and valine in winter barley, but varietal differences in grain N were not associated with significant changes in the amino acid composition of grain protein.

The nutritive values of spring barley, winter barley and winter wheat were compared in digestion and N balance studies in growing pigs. A subset often samples was examined which included, for each cereal type, high- and low-protein varieties, each (except for spring barley) grown with high or low rates of applied fertilizer N.

Apparent digestibility of dry matter measured at the terminal ileum was similar (0·67–0·70) in all three types of cereal but there was a tendency for the DM of high-protein varieties to be digested better than that of low-protein varieties. Over the whole digestive tract, the apparent digestibility of the DM of wheat was higher (0·83) than that of barley (0·75).

The apparent digestion of the starch of all samples was virtually complete (0·98) by the end of the ileum; the remainder was digested in the large intestine.

The apparent digestibility of N up to the terminal ileum was significantly higher for wheat than for barley, and significantly higher in high- than in low-protein varieties. Over the whole gastro-intestinal tract, the difference between the cereals was even larger; a greater proportion of wheat N than of barley N was digested in the large intestine.

The rate of N fertilizer application did not significantly affect the apparent digestibility of any amino acid but there were significant differences amongst the cereal types in the apparent digestibility of seven amino acids. The amino acids in high-protein varieties were, on average, 6 % more digestible than those in low-protein varieties.

When allowance was made for the endogenous flow of amino acids, some of the differences between cereals and between high- and low-protein varieties disappeared but some significant differences remained.

The biological value (BV) of wheat protein (0·43) was significantly lower than that of barley protein (mean 0·57). When pigs were fed wheat as the sole protein source, the higher N content of wheat compensated for its lower BV. There were no significant differences in the rates of N retention between pigs fed on wheat or barley.

Linear measurements of the length and maximum width of terminal leaflets of mungbean (Vigna radiata (L.) Wilczek) were made to estimate the whole trifoliate leaf area. The linear measurements were compared with the areas of leaflets and whole trifoliate leaves, determined using a leaf area meter. Five varieties were used in the study. Varieties differed in leaf shape and size, and equations were generated for each of the varieties to estimate the leaf area as a function of the product of the length and maximum width of the terminal leaflets, thus providing a means of nondestructive estimation of leaf area.

The effects of adding a culture extract from Aspergillus oryzae (AO) to the fermentation of a basal ration were investigated using the rumen simulation technique (Rusitec). The ration consisted of hay, barley, molasses, fishmeal and a minerals/vitamins mixture, at 500, 299–5, 100, 91 and 9–5 g/kg dry matter respectively. AO eliminated the transient fall in pH that occurred following the addition of substrate to Rusitec, but had no influence on the buffering capacity of the medium. Increases in the acetate: propionate ratio and in the proportion of butyrate in the fermentation products were observed in vessels receiving AO. Ammonia concentrations increased by over 30%. The number of total viable bacteria almost doubled and the cellulolytic population increased three-fold in vessels receiving AO. Protozoal numbers were reduced by almost 45% by AO. The proportion of methane in the headspace gas collected from the vessels during the day was significantly (P < 0·01) lower in vessels receiving AO. These results demonstrate that AO has a marked effect on the microbial population and the stoichiometry of the rumen fermentation, and that these changes can be seen in an in vitro system.

To investigate whether late pregnancy results in increased resistance to insulin action in ewes, a group of 18 crossbred ewes (six with twin foetuses) were given intravenous injections of glucose (0·25 g/kg) and insulin (0·25 U/kg) about 18days before full term and again during lactation, about 36 days after delivery. Before the injections, basal plasma concentrations of glucose, free fatty acids and growth hormone were lower during pregnancy than during lactation, but insulin concentrations were similar on the two occasions and cortisol concentrations were higher during pregnancy.

Rates of glucose removal and insulin secretory responses to the glucose injection were similar on the two occasions, both in ewes with single lambs and in those with twins. Insulin injection also resulted in similar decreases in glucose concentration on the two occasions in all ewes. Recovery from hypoglycaemia was somewhat delayed during pregnancy whencompared with lactation, but less so than in wether sheep given a similar injection of insulin. The plasma free fatty acid concentration decreased more slowly after glucose injection during pregnancy than in lactation. Responses of plasma cortisol concentration toinsulin-induced hypoglycaemia were similar on the 2 days, but plasma growth hormone concentration increased far more in lactating ewes after both injections.

The results did not indicate increased antagonism to insulin action in ewes during late pregnancy, but did show that changes in the counter-regulatory hormones after the disturbances to glucose homeostasis may differ markedly in the two situations and suggest that hyper-responsiveness of the system regulating growth hormone secretion contributes to the increased plasma growth hormone concentration observed in lactating animals.

Silastic implants of different lengths (0·5–4 cm) containing oestradiol were implanted in wether or ewe lambs, which were slaughtered at 14 or 23 weeks of age. Live weight gain and carcass weight of lambs was increased marginally by oestradiol treatment. Oestradiol decreased the percentage of fat in the carcass, while increasing the percentage of carcass water. Older lambs had a greater response to oestradiol treatment for the weights of the carcass protein and ash. The female reproductive system was affected by oestradiol with the ovarian weights being depressed and the uterine weights increasing. The uterus was especially sensitive to oestradiol at 14 weeks of age. Oestradiol increased the weight of protein in lamb carcasses, especially in the older lambs of this study.

In a field which had been grazed by dairy cows for 26 years, the bulk density of both total soil and fine earth increased rapidly with depth down to 10–12 cm, but decreased below this depth. The bulk density was approximately twice as great in the 10–12 cm as in the 2–4 cm layer. Total porosity in the 10–12 cm layer was only 22%.

Slitting the soil to penetrate the compacted layer approximately doubled net herbage accumulation and the net uptake of N, P and K, raising herbage production and uptake of nutrients from a low level to an acceptable one. Slitting tended to increase the concentrations of nitrate-N and K in herbage, but had little effect on the concentration of total N. Slitting increased the weight of ash-free root in the 10–20 cm depth range.

The C3 and C4 plant components in extrusa samples from oesophageally fistulated cattle can be estimated by δ13Canalysis. However, contamination with saliva containing bicarbonates could cause bias in the estimation of the C3 or C4 components. Saliva from animals fed C4 and C3 diets had δ13C values of – 4.37/103 and –15.97/103, respectively. Both values showed a large positive shift of c. 10 units relative to the diets, but the difference between feeds was maintained in the saliva. On theoretical grounds, contamination of the ingested feed with saliva should have caused a small (1·3–3·4% legume) negative bias when estimating legume percentage in the diet. This did not occur when saliva of known (PC was added to mixtures of C3 and C4 forages which were dried, ground and analysed for δ13C. It is postulated that CO2 was lost from bicarbonate when saliva was dried in contact with fresh plant material, and so no significant bias was detected. It would appear that the δ13C technique can be used to estimate the proportion of C3 and C4 components in oesophageal extrusa samples without significant bias from salivary contamination.

A two-year field experiment on a mollisol at Pantnagar showed that organic sources of N gave generally higher rice yields than the equivalent split dressing of prilled urea (PU). In 1985/86, Sesbania green manuring (40 kg N/ha) and PU (40 kg N/ha) and, in 1986/87, Sesbania (40 kg N/ha) + Azolla (40 kg N/ha) gave significantly higher yields than a split application of 80 kg N/ha as PU. Yield increases were attributed to significant variations in panicles/m2, filled spikelets/panicle and nitrogen uptake by the crop. These components, and grain yield, were significantly correlated with wet soil NH+4-N, which was increased by organic manuring. Wheat grown after each rice crop showed significant residual effects of the different sources of N applied to rice.

The growth and yield of maize grown on an unploughed newly opened secondary forest in Nigeria in 1985–87 was studied. In each year, trash was either removed or burnt in situ and each of these treatments was given N fertilizer or none. In the first year, only N fertilizer increased yields. In the second and third years, yields were increased by N fertilizer and by trash burning. Trash burning consistently increased the amount of P in the soil.

Four adult (4·5–7 years old) swamp buffaloes (Bubalus bubalis)and four adult (4–5 years old) Ayrshire cattle (Bos taurus) were housed in climate chambers maintained at 20° or 33 °C and given ad libitum access to a medium-quality, complete pelleted diet (AA6) or a lower-quality pelleted diet of alkali-treated barley straw supplemented with urea, sulphur, minerals and vitamins (ATS). Using a balanced double cross-over design, each animal was studied at each temperature and whilst consuming each of the two diets in experimental periods lasting 20 days. On day 13 of each period, animals were given single doses of two nonabsorbable markers, and food intake and complete collections of faeces were measured for the remainder of the period. Blood samples were taken at the end of each period.

Voluntary food intakes on a per kg body weight (W) or per kg W0·75 basis were significantly higher for the cattle than for the buffaloes, although this difference was reduced with the lower-quality diet and at the higher temperature. Cattle appeared to be more heat stressed at 33 °C than the buffaloes, but species had little effect on digestion or gastro-intestinal mean retention time. Calculations suggested that a greater proportion of digestion of ATS than of AA6 occurred postruminally.

A 4 x 4 Latin square design experiment was performed at the Ruminant Research Centre, Cockle Park Farm, University of Newcastle upon Tyne, in 1986 to determine the effect of grinding molassed sugarbeet pulp (MSBP) to varying degrees of fineness on overall apparent digestibility in wether sheep when the product constituted 90% of dry matter intake. A product (designated S) consisting of the pelleted screenings of unground MSBP was significantly less digestible than the other three products. No significant difference in overall apparent digestibility was observed between unground, coarsely ground and finely ground MSBP prepared from the same batch.

In a 4 x 6 randomized block design experiment, mature wethers equipped with rumen, duodenal and ileal cannulae were fed, in two meals, 1000 g concentrates and 100 g chopped hay per day. The concentrates consisted of 820 g mixture of barley and MSBP, 167·5 g soyabean meal, 10 g vitamins and minerals and 2·5 g chromic oxide per kg (fresh weight). The ratio of MSBP: barley was 1:3, 1:1 or 3:1 and the MSBP was either unground or finely ground. The aim was to determine the effect of replacing MSBP with barley on the nature of the rumen fermentation, overall apparent digestibility of the diet and the efficiency of rumen microbial protein synthesis (using 35S as a microbial marker).

There were no significant differences between the six diets in overall apparent digestibility of dry matter and organic matter, but N digestibility increased significantly (P > 0·05) as barley replaced MSBP in the diet. As before, the particle size of MSBP had no effect on overall apparent digestibility of the diet. The quantity of microbial N was reduced (nonsignificantly) and the efficiency of rumen microbial protein synthesis decreased (P > 0·05) compared with the other treatments when sheep were fed diets in which the ratio of MSBP: barley was 1:1. The particle size of MSBP had no effect on these factors.

As barley replaced MSBP in the diet, the mean pH of rumen fluid, calculated over 24 h, tended to decrease and there was a significant increase (P > 0·05) in the length of time that the rumen fluid was below pH 6. There were no significant differences between treatments in the concentration of ammonia-N in the rumen fluid. The dilution rate of rumen fluid (measured using 14C-Cr EDTA and Co EDTA as markers) decreased (P > 0·05) when MSBP replaced barley in the diet, and ground MSBP gave rise to lower (P > 0·05) dilution rates than unground MSBP. There were no significant differences between treatments in the ruminal concentration of total volatile fatty acids (VFAs) or the proportions of individual VFAs.

Use of a one-dimensional neighbour method of analysis in 1019 variety trials of a range of crops conducted by plant breeders in four states of Australia in 1985–87 resulted in an average reduction of 42% in variances of varietal yield differences compared with conventional randomized complete block analysis. Of these trials, 219 were designed as square, rectangular or generalized lattices and the average reduction in variances of varietal yields with incomplete block analysis and recovery of interblock information was 33%. The results emphasized that plots should be wide enough to avoid interplot competition, and that neighbour analysis is of most benefit in trials with short plots or when the field layout has many plots in a row.

Root biomass of timothy grass (Phleum pratense L.), at low and high N fertilization rates, and of red clover (Trifolium pratense L.) were estimated with soil cores and in mesh bags in a field trial on a sandy loam in central Sweden. First and second full-harvest year leys were sampled three times each year from May to October. Mesh bags were inserted in the soil in autumn shortly after sowing (longterm bags); in spring and autumn of the first year and in spring of the second year (medium-term bags); and every third month during both years (short-term bags). Mesh bags of each type were sampled when the soil cores were taken.

Root biomass in the long-term bags was generally about the same as that in the soil cores, but taproot biomass in the clover crop was underestimated in the bags. In the grass plots, differences between soil cores and mesh bags were probably caused by ingrowth of weed roots in bags and by larger root biomass in plant rows than between rows. If soil cores and long-term mesh bags are sampled in exactly the same way identical estimates of biomass should be obtained.

Root biomass in short-term and medium-term bags was about the same as that in the soil cores and long-term bags on many of the sampling occasions. Thus a stable level of biomass was reached in a rather short time, i.e. after 3 months or less. Then root production, root mortality and root decomposition occurred simultaneously at a fairly constant level.

The bags did not contain residues from earlier crops, which reduced the amount of separation work necessary. The absence of crop residues in the bags did not seem to affect root biomass.

The mesh bag method is a useful alternative to soil core sampling for studying root biomass and root dynamics in perennial and annual crops. However, the bags must be inserted into the soil just after sowing and they must be placed in, as well as between, plant rows.

Two small-grained cereals, Mulga oats and a triticale line, and two legumes, local vetch and local peas, were grown in pure stands and in mixtures at various cereal: legume seed ratios (20:80, 40:60, 60:40 and 80:20) for three successive cropping years, 1981/82 to 1983/84, at Laxia and Dromolaxia, Cyprus, in each year.

The cereal pure stands produced, on average, more dry matter, 8·40 t/ha, and more digestible organic matter, 4·12 t/ha, than the legume pure stands, 3·68 and 2·18 t/ha, respectively. On average, total dry matter production decreased linearly as the seed proportion of the legume component in the mixture increased. The proportion of the legume in the harvested material was much lower than expected from the seed ratios. The highest proportion of legume was seen in the mixtures of peas with triticale and ranged from 8·1 to 35·5% at the various sowing rates. Digestibility and crude protein content were highest in the mixtures of triticale and peas.

Water metabolism of two breeds of sheep (Uda and Yankasa)and two breeds of goat (Sahel and Maradi) was studied. Tritiated water space as a percentage of live weight was 80·5 and 73·6 % for Uda and Yankasa, respectively, and 77·8 and 66·1 % for Sahel and Maradi, respectively. The biological half-life of tritium was least in Yankasa (115 h) and longest in Sahel (173 h). Water turnover (I/day per animal) was 2·52, 2·63, 0·86 and 1·09 for Uda, Yankasa, Sahel and Maradi, respectively.

In 2 years two groups of 32 grazing cattle were used to examine the effects of previous grazing treatment and of body size on grazing behaviour and herbage organic matter intake (HOMI). Compensatory intake resulted from differences in grazing time only in the first year. There were no sex differences in intake when account was taken of differences in mature size raised to the power 0·73. Bite weight was related to the degree of maturity by the allometric coefficient of 0·46, and HOMI was similarly related by the coefficient of 0·36. This accords with the predicted effects of restricted grazing conditions on animals of different weight, and with allometric changes with weight in incisor breadth. Decreases in intake under grazing were similar in animals differing in maturity and weight. It is suggested that under constant grazing conditions the change in grazed herbage intake as animals mature reflects the allometric change in bite weight and a corresponding decline in bite numbers, resulting in consumption of a constant proportion of ad libitum intake.

Herbage and oil yields of Mentha arvensis (Japanese mint), M. piperita (peppermint) and M. spicata (spearmint) increased significantly with N fertilization up to 100 kg N/ha and those of M. citrata (bergamot mint) with up to 150 kg N/ha. Plant height, leaf: stem ratio and leaf area index increased with N application; and oil content decreased in all the species. Economic optimum doses of N for M. arvensis, M. piperita and M. spicata were 167, 153 and 145 kg N/ha, respectively and their oil yields expected from the response equation were 190, 103 and 50 kg/ha, respectively. The calculated optimum fertilizer rate for M. citrata was 225 kg N/ha, giving a yield of 193 kg oil/ha. Oil quality did not vary appreciably with N fertilization.