Friesian bull calves, 2 weeks old, were given an experimental diet of cow's milk supplemented with phosphorus to provide three rates of P intake: adequate, high, and very high. After 1 week's preliminary feeding, studies of absorption, endogenous secretion, urinary excretion, serum concentration, retention and kinetics of Ca and P metabolism were made by a balance and dualradioisotope technique with 32P and 45Ca.

The efficiency of P absorption decreased significantly as the P intake increased and the highest absorption efficiency was 96% on the unsupplemented milk diet. Endogenous faecal excretion of P was low on all treatments. Urinary P excretion was substantial even on the milk-only diet and increased further with supplementation of P. The efficiency of absorption of Ca remained constant, and urinary Ca excretion was low in all the groups. Serum P and Ca concentrations did not vary significantly but there was a significant decrease in the retention of P and Ca as the P intake increased.

Although urinary excretion appears to be the main process responsible for P homoeostasis in preruminant milk-fed calves, some regulation of the efficiency of absorption of P according to the P intake may also occur.

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.

In two experiments the yield, digestibility, protein and cell wall contents of several autumn-sown triticale cultivars were compared with rye at defined growth stages. Yields at each growth stage were highest in the triticale cultivars. The content of leaf blade and sheath fell with increased maturity while stem and ear content increased. There were differences between cultivars in the contribution of individual stem internodes. Digestibility also declined with maturity for all plant parts, and differences were apparent between plant parts and between cultivars. Leaf blade showed a slow decline in digestibility whereas stem digestibility showed a rapid reduction so that, at growth stage 43, young stem internodes were of much higher quality than older ones. Spring-type triticales (A208 and A476) had the highest digestibility at stages from flag leaf emergence to anthesis. The relationships between digestibility, plant part contents and cell wall characteristics are discussed.

Twelve sheep were fed semisynthetic roughage diets at three rates to study the effects of intake of dry matter, concentration of phosphorus and the physical form of two low-P barley straws upon the faecal losses of P. The sheep were in negative P balance throughout the experiement. The absorption of dietary P increased with P intake and was unaffected by differences in the physical form of the roughage. For each barley straw diet, endogenous faecal P increased with dry matter intake, and was higher when the roughage was ground than chopped. Over the whole experiment, daily endogenous faecal P ranged from 8·5 to 31·5 mg/kg live weight. Endogenous faecal P was related to P intake or to dry matter intake and plasma inorganic P. The concentration of faecal endogenous P was negatively related to the intake of each diet. It is concluded that the concentration of inorganic plasma P and the rate of salivary secretion are responsible for the endogenous faecal excretion of P and the regulation of P balance in sheep fed low-P diets.

In a 2-year field study, leguminous fodder crops (cowpea (Vigna unguiculata) and cluster bean (Cyamopsis tetragonoloba)) responded more to P than did nonleguminous fodder crops (maize (Zea mays), sorghum (Sorghum bicolor) and pearl millet (Pennisetum americanum)). The local cultivar of tall wheat, C306, yielded more when sown after fallow or legumes than after nonlegumes. Wheat sown after fallow or legumes produced more ear-bearing tillers and more grains per ear than when sown after nonleǵumes. Wheat sown after fallow or legumes responded to N application of up to 20 kg/ha, while when sown after nonlegumes it responded linearly to the highest rate of 60 kg/ha. Thus, preceding fallow, cowpea and cluster bean reduced the N requirement of wheat by 20–40 kg/ha compared with preceding maize, sorghum and pearl millet. Nitrogen increased grain yields only at applications of up to 40 kg/ha because lodging occurred at the higher rates. A cluster bean-wheat cropping sequence proved the most profitable.

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.

In a 2 × 4 factorial experiment, the laying performance of hens given diets with or without blood meal and four concentrations (0, 5·71, 11·43 and 17·14 g/kg) of added magnesium chloride was measured for 280 days. The inclusion of 50 g/kg blood meal in the laying diet reduced the rate of laying (P < 0·05), egg weight (P < 0·01), egg output (P < 0·01), food intake (P < 0·01), body weight gain (P < 0·01) and body weight at 457 days (P < 0·05). It increased the height of albumen (P < 0·05), Haugh unit score (P < 0·01) and shell colour intensity (P < 0·05) of fresh eggs. The inclusion of increasing dietary concentrations of magnesium chloride reduced (P < 0·01) the specific gravity of eggs but had no significant effect on any of the other egg quality or production characteristics. The dietary treatments had no significant effect on Haugh units of stored eggs.

The responses to treatment with chlormequat of winter oats at various rates of applied N were investigated in field experiments over two seasons. Chlormequat, applied at crop growth stage (GS) 32, significantly reduced stem length by an overall average of 25·3% in 1985/86 and 27·4% in 1986/87. The percentage reduction was not significantly influenced by variety or by the rate of N applied. All intcrnodes apart from the basal one were significantly shortened. The third internode from the base showed the largest percentage reduction and the uppermost internode the largest actual reduction in length, in all three varieties. Stem shortening was always associated with an increase in the weight per unit length of stem. In 1985/86 lodging in untreated control plots became more severe as N rate increased, but was completely controlled by the application of chlormequat at all but the highest rate (150 kg N/ha).

Combine-harvested grain yields of the variety Pennal in 1985/86 and of Bulwark and Pcnnal in 1986/87 were reduced where chlormequat had been applied. Hand-harvested samples from these treatments did not show the same reductions in yield, but revealed a significant increase in the number of grains per panicle and a significant reduction in their mean individual weight. The grain characteristics of Peniarth were unaffected.

The lengths of the main-stem panicles and primary branches in the panicle were shortened as a result of chlormequat application. In addition, the degree of branching and the number of spikelets were increased in the lower third of the panicle but reduced in the upper two thirds. In both Bulwark and Pennal the numbers of sterile grains were increased by the application of chlormequat and, in Bulwark only, the number of fertile grains was reduced. In Peniarth the numbers of fertile and sterile grains were unaffected.

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.

Three pot experiments were performed in unheated glasshouses at the University College of North Wales College Farm, Aber, Gwynedd in 1980–1983. Two experiments tested the effects of sowing date and N supply, the third sowing density and nitrogen supply. Extension growth of main-stem leaves was measured by ruler and expressed in thermal time units to allow comparisons between sowing dates. Rate and duration of leaf extension were determined from linear regressions of leaf length against thermal time.

Increasing N supply increased leaf extension rate but had no significant effects on leaf extension duration. Leaf extension rate increased with leaf position on the main shoot, but decreased slightly in leaves extending at the time of stem elongation. Leaf extension duration also increased with leaf position on the main shoot and was related to mean temperature during the leaf extension phase. Plants sown in September were able to compensate for lower radiation receipts by having a faster rate and longer duration of leaf extension, by producing larger leaves with a greater specific lamina area and by partitioning a greater proportion of extension growth into lamina and less into sheaths. In plants sown in June, the largest leaf occurred at a lower stem node and leaves emerging later showed a strong response to N. It is suggested that this is attributable to earlier onset of internal competition for assimilates. Variation in leaf extension rate was the main factor influencing variation in final leaf area. There was a strong positive relationship between leaf extension rate and leaf N content.

Increasing sowing density increased the area of the first four leaves on the main shoot and decreased that of later leaves, changes mainly associated with changes in leaf extension duration. It is concluded that progress in the modelling of leaf area expansion, light interception and dry matter production requires more information about how sowing date, sowing density and N supply interact to influence crop development and leaf growth.

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.

Immunoreactive (I) and biologically active (B) luteinizing hormone (LH) was measured in jugular vein and carotid arterial plasma of four cows 110–140 min after luteinizing hormone releasing hormone (LHRH) injection. Plasma was separated on Ultragel AcA54 and fractions corresponding to those containing authentic bovine luteinizing hormone (bLH) were assayed. Immunoreactivity in venous or arterial plasma occurred mostly in fractions corresponding in molecular weight to bLH. Low activity was measured in several other fractions. Biological activity was also high in the same fractions from venous plasma, though it was not so pronounced in arterial plasma.

A veno-arterial difference across the head for immunoreactive LH was found in all animals, and there was a significant difference in biologically active LH (mouse Leydig cell assay). The mean B:I value for immunoreactive LH was similar in venous and arterial plasma for three out of four animals, 0·72 and 0·66, respectively. In a fourth cow with a clinical history of infertility, the B:I value was low in both venous and arterial plasma, 0·19 and 0·08, respectively. The results indicate that infertility in this latter instance was associated with LHRH-induced secretion of a compound similar in molecular size and immunoreactivity to LH but deficient in biological potency.

Effects of inflorescence removal under different plant densities and degrees of shading on seed yield of field beans (Vicia faba L.) were investigated. Two indeterminate cultivars were used in field experiments for two seasons (1985 and 1986). The hierarchy within the generative storage system of field bean plants was manipulated by removal of inflorescences at various growth stages and nodes.

Removal of the inflorescences of nodes 1–3 (counted from the base upwards) caused about 30% loss of seed yield potential compared with the control but compensatory increases in seed yield were found, differing with plant density and duration of shading. Under favourable growing conditions (no shading, 20 plants/m2), overcompensation occurred, giving a mean seed yield up to 40% more than in controls.

Removal of all inflorescences above the ninth flowering node did not significantly reduce seed yield as plants completely compensated for the restriction on yield imposed.

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.

Three in vitro methods, one enzymic and two microbial, were applied satisfactorily to the determination of the dry matter digestibility of forages, but failed when applied to a variety of concentrate feeds. The microbial methods had the advantage that the proportion of weight lost from forages during the in vitro process approximated closely with their determined in vivo digestibilities.

The microbial method based on sheep faeces was as effective as that using rumen liquor in digesting ruminant feedstuff's in vitro. Since sheep faeces are readily obtained from intact animals, the faeces liquor method would seem to have a distinct advantage in use.

Using closely related inbred lines, the effects of selecting for two contrasting seed types (desi and kabuli) and colours (brown and white) were determined for a number of agronomic and seed characters in chickpea. Plant establishment was 53% higher in desi types than in kabuli types, and 20% higher in brown-seeded lines than in white-seeded lines. Increased contents of tannins in testas of brown seeds were associated with the seed colour response, whereas the difference in establishment between desi and kabuli types was probably a function of the thicker desi testa. Differences in yield due to seed type and colour reflected differences in establishment, but were smaller in magnitude.

Seed type was clearly associated with testa fraction and fibre content. Desi seeds averaged 15·7% testa and 13·2% acid detergent fibre, but kabuli seeds contained only 6·7% testa and 5·6% fibre. In contrast, the crude protein content of kabuli seeds was 1·4 percentage points higher than that of desi seeds. Testa and fibre contents of brown kabuli seeds were significantly greater than those of white kabuli seeds, although the differences were smaller than those between desi and kabuli types.

Decortication was satisfactory for white desi seeds, but for white kabuli seeds it gave rise to highly fragmented cotyledons which were often contaminated with attached testa. Brown kabuli seeds produced a sample of intermediate quality. It is suggested that, with some genetic improvements and processing refinements, brown kabuli genotypes could be developed as dual-purpose chickpeas, having both culinary and stockfeed uses.

Growth and water use of kabuli-type chickpea was measured during the 1982/83 and 1983/84 growing seasons in northern Syria under rainfed conditions. Winter-sown (November) and springsown (March) crops of cv. ILC 482 were grown in 1982/83 while in 1983/84 spring-sown crops of contrasting genotypes (ILC 482, ILC 1929 and ILC 3279) were compared.

In 1982/83, shoot dry matter and seed yields of the winter-sown crop were almost twice those of the spring-sown crop although the water use of both crops was almost the same. Root growth of both crops was most rapid before flowering but continued until maturity (early June) in the winter-sown and until mid to late pod filling (also early June) in the spring-sown crop. Root dry weight (c. 45 g/m2) and length (c. 45 cm/cm2) were similar in both crops during pod filling.

In 1983/84, shoot weight, root weight and root length were similar in all genotypes but the later maturity of ILC 3279 resulted in lower seed yield and hence harvest index, and greater water use.

The root length density decreased approximately logarithmically with depth in the soil profile although comparison between seasons and with other published results showed that the relations could not be used predictively. Water use efficiency was poorer in the second, drier season and was almost doubled by winter sowing.

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.

A Mediterranean grassland was grazed with beef cattle at 0·5, 0·67 and 0·83 cows/ha, all the year round for 5 years. Range forage became increasingly scarce during the dry season, especially at high stocking density, and more supplementation was needed to maintain the animals. Herbage consumption was calculated from standard requirements for recorded body weight and performance. Maintenance requirements were multiplied by a grazing activity factor of 1·6.

Mean annual herbage dry matter production was estimated at c. 3·06 ± 0·137 t/ha. Most of the variation between years was due to a particularly productive year in 1978. Contrary to expectation, stocking density had a small effect on total herbage production, despite significant differences in animal performance. It appears that herbage production of the seasonally temperate herbaceous range, typical of the basaltic hills in eastern Galilee in Israel, is not limited by total annual rainfall. Alternative limiting factors are nutrient deficiency and restricted rooting zone, or a combination of both.