Eighteen Double Muscled (DM), 18 Beef Synthetic and 18 Hereford bulls, serially slaughtered from approximately 250 to 800 kg live weight, were used to examine the influence of maturity type and Double Muscling on individual muscle growth patterns and distribution.

Breed types differed significantly in the relative growth rate of five of the 95 muscles. Individual muscles grew and developed at relatively different rates with muscles associated with locomotion being early developing followed by those associated with structure or posture and finally those which respond to sexual maturation or luxury muscles which were late developing. Individual muscle growth patterns revealed an increasing disto-proximal gradient along the limbs and an increasing caudo-cranial gradient along the whole body. However, within any anatomical region considerable variations with well defined growth gradients were found for individual muscles. In the proximal region of both limbs increasing medio-lateral growth gradients were apparent.

At the same total side muscle, breed types differed significantly in adjusted mean weights of 33 of the 95 muscles. When comparison was made at the same total side muscle, DM showed a range of hypertrophy of + 28% to -28% when compared with the more normal breed types.

Muscular hypertrophy followed a disto-proximal gradient along the limbs and an inner–outer gradient across the muscle layers with the superficial and bulkiest muscles being the most hypertrophied. At the same total side muscle, DM had heavier expensive or luxury muscles than normal cattle.

Experiments made with winter fodder crops, lucerne (Medicago sativa), berseem (Trifolium alexandrinum) and oats (Avena sativa) and summer fodder crops, cow pea (Vigna unguiculata), guar (Cyamopsis tetragonoloba), sunhemp (Crotolaria juncea) and pearl millet (Pennisetum americanum) showed that a sequential crop of Sudan grass yielded more after the legumes than after the cereal fodders, oats or pearl millet. The legume advantage was noted in the crop not given fertilizers but also when Sudan grass was given N fertilizer. The yield increase in Sudan grass grown after legumes was equivalent to 32–60 kg fertilizer N/ha applied to Sudan grass following pearl millet.

After harvesting the legumes more available N and NO3-N was present in the soil and the apparent recovery of fertilizer N by a subsequent crop was increased by the legume.

The application of chemical desiccants to lucerne and red clover after cutting is studied from the standpoint of increasing the drying rate in relation to pan evaporation. Significant increases in the evaporation-based drying constant are found on both first and second cuttings of these crops, but the savings of a full day's drying time is expected only for second-cut lucerne in the north-eastern U.S. climate. The effect of crop density on drying rate is also studied. In conjunction with a theoretical analysis, it is determined that the drying constant varies as γ-0.65, where γ is the areal density. The evaporation-based drying constant is then related to crop yield and the ratio of cutting width to windrow width.

A field experiment conducted for two cropping seasons (1976–7 and 1977–8) showed that a fodder crop of Egyptian clover (Trifolium alexandrinum) increased the grain yield of a subsequently grown maize crop. Lathyrus (Lathyrus sativus) and peas (Pisum sativum) were less effective in this regard.

In a study of the effect of animal species on the threshold particle size leaving the rumen, two grasses cut at two stages of growth and one mature legume were separated into leaf and stem fractions and fed to cattle and sheep. Samples of rumen digesta and faeces were used to determine the validity of using a 1·18 mm porosity screen to separate the rumen particles into large and small pools when studying escape of particles from the rumen. Samples of rumen digesta and faeces were collected for the determination of particle size by wet sieving and the calculation of resistance of particles to passage from the rumen relative to small particles retained on a 0·15 mm sieve.

Particles < 1·18 mm but > 0·5 mm had a mean relative resistance to passage of 2·0 and 2·6 for cattle and sheep respectively, compared with resistance values of between 10·9 and 31·2 for particles between 1·18 and 2·36 mm. It is suggested that there is no justification for using different threshold particle sizes for sheep and cattle and that a 1·18 mm sieve may be used to divide the rumen contents of both cattle and sheep into two pools of particles with high and low relative resistance to passage from the rumen.

Two field experiments examined the influence of soil nitrogen on grain yield, wateruse efficiency and residual nitrate accumulation of four winter grain legumes in a legume–fallow–wheat rotation. In the first experiment, conducted on a clay soil with a high total soil nitrogen content (0·194%), the three legumes Cicer arietinum, Vicia faba and Pisum sativum gave similar yields, with Lupinus angustifolius showing poor yields. Water-use efficiencies followed similar trends to the grain yields. Wheat yields and concentration of nitrogen in the grain, following a fallow after the legume crops, showed no differences from a full 2-year fallow. In the second experiment on a low fertility soil (0·081 % total soil nitrogen), Cicer arietinum gave the highest yield and the greatest water-use efficiency. All legumes and long fallow resulted in a similar increase in wheat yield when compared with a wheat-fallow-wheat rotation. The legume crops generally increased soil nitrate status between their sowing and the sowing of a wheat crop 2 years later; such increases were greatest with Pisum sativum at the high fertility site, with a suggestion of the reverse occurring at the low fertility site.

Two experiments were designed to measure the effect of current barley storage systems on vitamin E stability.

Whereas propionic acid and sodium hydroxide treatment of moist barley results in destruction of vitamin E, neither moisture per se nor anaerobic storage has such a detrimental effect. The destruction is most severe and rapid with alkali treatment, the reaction having substantially reached completion by 5 days. All the vitamin E isomers were affected to varying degrees, the order of susceptibility to decay being α-tocopherol > γ-tocopherol > α-tocotrienol > γ-tocotrienol.

Possible explanations are given as to why the findings incriminating propionic acid in vitamin E destruction are at variance with currently held opinion.

The isotope dilution technique was used to measure endogenous faecal excretion and absorption of dietary Ca and P by growing lambs. Groups of four lambs were given 0·8 or 1·2 kg/day of a pelleted barley and soya-bean diet containing 4·2 g P/kg D.M. and supplemented to contain 1·79, 3·52 or 4·67 g Ca/kg D.M.

At the lowest dietary concentration of Ca, absorption of Ca was insufficient to meet the Ca required for deposition in the newly formed bone matrix of the skeleton; retention was 0·39, 1·16 and 1·12 g/day with increasing dietary Ca concentration. The proportion of dietary Ca absorbed decreased (P < 0·001) with increasing Ca intake, ranging from 0·85 to 0·44. Endogenous faecal excretion of Ca was independent of the absorption of dietary Ca, but increased (P < 0·05) from 17·2 at the lower to 21·1 mg/kg live weight/day at the higher D.M. intake. Plasma concentration of Ca was higher for the female (2·51) than the male (2·33 mmol/1) lambs and increased linearly (P < 0·001) with dietary concentration of Ca from 2·31 to 2·52 mmol/l.

The retention of P increased with Ca and D.M. intake. On the other hand, the proportion of dietary P absorbed (0·85) was independent of Ca intake and hence of P retention. Increases in P retention were reflected by decreases in urinary P, but not in endogenous faecal excretion. Endogenous faecal excretion of P increased with D.M. or P intake from 17·9 at the lower to 33·5 mg/kg live weight/day at the higher intake.

The results are discussed in relation to dietary allowances of Ca and the mechanism of P homoeostasis.

The genetic structure of six rye (Secale cereale L.) cultivars bred as forage cultivars was investigated by means of nine isozyme loci. The isozyme systemselectrophoretically studied were glutamic oxaloacetic transaminase; phosphoglucose mutase; phosphoglucose isomerase; acid phosphatase; malic dehydrogenase and 6-phosphogluconate dehydrogenase. Alleles present and their frequencies were very similar in all cultivars; thus genetic distances between cultivars ranged from 0·000 to 0·005. Likewise, a general excess of homozygotic plants compared with the expected number was observed in cultivars. The genetic structure of these populations is closely similar to other rye cultivars, bred for grain production, which were previously analysed.

Data are presented for the amino acid contents of 64 litters of Suffolk × (Finnish Landrace × Dorset Horn) foetuses varying in gestational age from 90 to 145 days and in litter size from one to five. The concentrations of glycine, cystine, arginine, proline and hydroxyproline in foetal dry matter increased with age, those for threonine, serine, glutamic acid, valine and methionine remained fairly constant while those for aspartic acid, phenylalanine, histidine and lysine tended to decrease. The most pronounced of these age effects were for cystine and hydroxyproline which increased in concentrations by 60 and 100% respectively over the final 2 months of foetal life. The rates of accretion of the individual amino acids are discussed in relation to estimates of the amounts that may be supplied by microbial protein.

Fertilizer nitrogen recovery under fallow and under a wheat crop (Triticum aestivum L., cv. Miriam) grown on a deep loessial silty loam (Calcixerollic Xerochrept), was studied with 15N labelled KNO3. The labelled nitrogen was applied (at a rate of 180kg/ha) to 30 cm diameter microplots enclosed in hard plastic tubes that protruded 5 cm above the soil surface. In the 1st year of the experiment there was a long dry spell during the main part of the growing season and plant dry-matter yields were low. The 2nd year was wet, with heavy rain early in the season. About one-third of the fertilizer N applied to the fallow was lost from the top 60 cm layer in the 1st year. Most of the fertilizer N remaining in the soil as mineral N at the end of the first season was lost in the 2nd year. The possible reasons for such low N-conservation efficiency are discussed.

Sulphur deficiency reduced the yield and sulphur content of ryegrass at the fourth cut, while increasing the nitrogen content and N:S ratio. The distribution of the forms of nitrogen was also altered, with a decrease in the proportion of nitrogen recovered as amino acids and an increase in the concentration of asparagine. Amino acid analysis showed that the concentrations of the sulphur-containing amino acids cyst(e)ine and methionine were depressed by sulphur deficiency as well as those of arginine, histidine, lysine, glycine, leucine, serine and threonine. Sulphur deficiency, therefore, decreases the quality of crude protein found in grass, as well as reducing the yield.

The objective of this work was to investigate the effects of changing proportions of readily fermentable carbohydrate and fibre in the diet on the rates of lipolysis and fatty acid hydrogenation by sheep rumen digesta. Three experiments were carried out using rumen-fistulated Romney wethers. In the first experiment rumen digesta from one sheep on a high-fibre diet was incubated in vitro with [1–14C]linoleic acid and 0, 0·1, 0·2 and 0·5% sucrose. It was found that sucrose increased the rate of hydrogenation of linoleic acid by up to 40%.

In the second experiment five rumen-fistulated Romney wethers were fed five diets according to a latin-square experimental design. These diets had decreasing proportions of fibre (42·8–19·5%) and increasing proportions of starch (12·2–35·7%). Lipolysis and hydrogenation rates decreased significantly with decreasing fibre content which was reflected in the amounts of stearic and octadecenoic acids in the rumen digesta.

In the third experiment sheep were fed the high-fibre diet used in the first experiment and the rumen digesta incubated in the presence of 0, 0·15, 0·45, 0·75 and 1·50% starch. Lipolysis rates increased but no effect of added starch on hydrogenation was observed.

It was concluded that the short-term addition of energy to the rumen digesta increases lipolysis and hydrogenation rates. However, long-term replacement of fibre by starch results in a reduction of these rates.

Comparisons were made of the tuber yield and leaf morphology of three dihaploids, their chromosome-doubled derivatives and tetraploid parthenogenetic parents grown in a glasshouse at low, medium and high fertilizer levels. Differences in yield between the dihaploids and doubled dihaploids were not significant (P > 0·05) and responses to increases in fertilizer were similar. Leaf complexity showed generally large (usually significant, P< 0·05) increases when the fertilizer level was increased from medium to high. For the heterozygous tetraploid parents the tuber yield increased more than leaf complexity. Probably the dihaploids and doubled dihaploids utilized the additional fertilizer to increase foliage growth rather than tuber yield whereas the converse was the case for the tetraploid parents. There was no evidence that chromosome doubling resulted in changes in the response of dihaploid genotypes to changes in the fertilizer level.

A quantitative description of the factors underlying seasonal changes in herbage digestibility is developed and applied to sets of data from S. 24 and S. 23 perennial ryegrass. A new variable, relative maturity, is used to describe the effect of defoliation in interrupting the process of tiller maturation which leads to the decline in digestibility. For S. 24, the model explained 95·5% of variation in digestibility decline, R.S.D. = 1·07, allowing accurate prediction of digestibility. For S. 23, 87·5% of variation was explained, R.S.D. = 1·85. The model for S. 24 also worked well on data from a different site, nitrogen level and cutting regime, and the question of the model's generality is discussed. Relative maturity appears to be a useful concept in describing the physiological maturity of swards under different harvesting regimes.

A hyperbolic model relating crop yield to weed density is extended to include crop density as a further variable. Other models were obtained from published sources, eight being originally applied to yield of above-ground biomass and six to marketable yield. Data were obtained from a field experiment in which spring wheat and spring barley were planted either in monoculture or together and at a range of densities. Further data were obtained from a published experiment on Sinapis alba and barley grown in containers. The models were fitted to data using maximum likelihood estimation. Comparisons of residual sums of squares showed that for the wheat and barley field experiment biomass yield and marketable yield were sufficiently described by a three-parameter model. The Baeumer & de Wit (1968) equation proposed for replacement series experimental designs is considered reasonable for the analysis of field additive designs provided the parameters are interpreted in agronomic terms. For the Sinapis alba and barley experiment more complex models could be justified.

The honeybee alarm pheromones 2·heptanone and isopentyl acetate were repellent to honeybee foragers when applied to plots of oil-seed rape and field beans and to sunflower heads. Their possible use to repel bees from crops before insecticide application is discussed.

Sorghum bicolor, Pennisetum americanum, Echinochloa utilis, Panicum miliaceum, Setaria italica and Eleusine coracana were grown with and without full irrigation on an alkaline clay soil at Trangie, Australia. Dry-matter yields and forage quality changes with time were measured in the 1st year. Grain yield was recorded over 2 years.

Dry-matter accumulation was initially most rapid in sorghum and Japanese barnyard millet. Sorghum, pearl millet and finger millet produced the most dry matter; these were the latest to reach head emergence. The early-maturing proso millet and foxtail millet produced only 7 and l i t dry matter/ha respectively. These two millets, like sorghum and pearl millet, had a high nitrogen: sulphur ratio and low sodium concentration in the forage. Finger millet had a lower nitrogen: sulphur ratio and a sodium concentration that was surpassed only by Japanese barnyard millet.

Irrigated sorghum consistently produced the highest grain yields: over 9 t/ha. Yields from the millets were: foxtail 6·0, finger 5·0, proso 3·5, pearl and Japanese barnyard millet 2·8–2·9 t/ha. Special features of the millets are discussed.

The proteins and the amino acid profile of the rumen fungi Neocallimastix frontalis and Piromonas communis have been examined and the in vitro digestibility of the vegetative growth determined.

The mean true protein content of N. frontalis was 24% of the dry weight and 30% for P. communis, which has a lower chitin content. 50% of the protein extracted from cells and examined by HPLC was in the 200000 MW range and 40% in the 50000 MW range. Polyacrylamide gel electrophoresis after treatment with sodium dodecylsulphate and 2-mercaptoethanol indicated that the native proteins were composed of smaller units in the MW range 25000–50000.

The amino acid profiles of the two fungi were similar and compared favourably with those of casein and fraction 1 protein of lucerne.

Azospirillum brasilense was treated with nitrosoguanidine and five antibiotic-resistant mutant strains isolated. Variations in growth, N2-fixation, ultraviolet-dark survival and level of antibiotic resistance were found between the mutant strains. Mutant strains STR 112 and KR 2051 showed maximum nitrogenase activity, glutamine synthetase activity and hydrogenase activity (H2 uptake) at 32 °C and 40 °C respectively. Inoculation of cheena genotypes with A. brasilense and its mutants led to significant increase in associative nitrogen fixation, dry weight of roots and grain yield compared with the uninoculated control, with significant strains × genotypes interactions in calcareous soil. It was also noted that under laboratory conditions Azospirillum inoculation may have produced its response by hormonal means and/or associative N2-fixation.