One side of each of 51 carcasses of Hereford, Angus, Friesian and Charolais cross-bred steers was dissected and the weights of individual muscles and total carcass muscle were obtained. The percentage distribution of total carcass muscle weight in muscles and in. standard groups of muscles was determined. In addition, the percentage distribution of total carcass muscle weight in wholesale cuts was determined from the weights of whole and part muscles specified as comprising the respective cuts.

Minor breed differences only were found in muscle weight distribution among muscles, groups of muscles and wholesale cuts. Similarity of muscle weight distribution in the different types of carcasses studied shows that carcass shape is not associated with differences in the distribution of muscle weight in wholesale cuts.

S. 24 perennial ryegrass, containing 2·9 g nitrogen/100 g D.M.>, was conserved by freezing (to represent the fresh material) or by drying. Three dehydration treatments were imposed, comprising low temperature (inlet temperature 145 °C) high temperature (inlet temperature 900 °C) or oven drying (100 °C for 18 h) and in addition part of the high temperature dried grass was treated with formalin (1 g/100 g crude protein) prior to feeding.

The digestion of the energy and nitrogen components of all diets was investigated using sheep fitted with re-entrant cannulae at the proximal duodenum and terminal ileum.

Dehydration and formalin of the grass reduced nitrogen solubility and apparent energy and nitrogen (P < 0·001) digestibilities but led to increased quantities of nitrogen entering the small intestine (P < 0·01) compared with the frozen diet. A significant relationship describing nitrogen transformations was established: Y = 165–1·13X (r = –0·98, P < 0·001), where Y is g nitrogen entering the small intestine per 100 g N consumed and X is dietary nitrogen solubility. All dried diets showed increased losses of nitrogen within the small intestine compared with the frozen diet, the largest values being observed on the oven-dried and formalin-treated diets.

Neither total VFA production within the rumen nor overall cellulose digestibility was influenced by dehydration, but on the formalin-treated diet there was a marked shift of cellulose digestion from the rumen to the caecum and colon compared with the other diets, associated presumably with the large reduction in protein solubility on this diet.

Dehydration improved the efficiency of conversion of ruminally digested energy to VFA energy within the rumen, and in relation to the nature of the total absorbed nutrients a significant relationship was established:

Y = 30·97–0·22X (r = –0·98; P < 0·001),

where Y is g digestible crude protein lost in the total intestines per 100 g digestible organic matter intake and X is dietary nitrogen solubility.

A number of studies on sodium hydroxide treatment of rice hulls and straw are reported. Alkali levels ranged from 0 to 100 g NaOH/100 g for hulls and from 0 to 50 g NaOH/100 g for straw.

Effects of prior grinding, prior irradiation with gamma rays (0–50 Mrads), alkali reaction time (0–24 h), neutralization of excess residual alkali with acids, and rinsing effects were studied in terms of increased salt (ash) content, test material solubility in water and in vitro and in vivo (terylene bag) fermentation.

Moderate increases in solubility and digestibility of straw followed irradiation but not for hulls. Major increases were found for irradiated straw further treated with alkali but hulls were little affected by 5 g NaOH/100 g D.M. except at the 50 Mrad level. Nutrient fortification of inocula media did not help dissimilation. Grinding had little effect on degradation of alkali-treated hulls. Straw responses were greater than for hulls.

Alkali treatment removed encrusting silica and lignin from rice hulls and increased in vitro and in vivo digestibility. Above levels of 12·5 g NaOH/100 g dry matter in vitro digestibility was depressed unless residual alkali was neutralized. Alkali-treated hulls were reduced in silica content better by rinsing or by no neutralization and no rinsing: neutralization or neutralization followed by rinsing were less effective. Lignin was best removed by alkali or alkali and acid without rinsing. Alkali reaction time on hulls was not critical, but alkali concentration was.

Animal trials indicated useful intake and digestive responses to alkali-treated rice hulls. Raw rice hulls were rejected by sheep.

When fed in a mixed diet with lucerne chaff (40% whole rice hull, 60% lucerne chaff) daily voluntary intake of rice hull dry matter was 345 g (nil NaOH); 361 g (10 g NaOH/ 100 g rice hull); 193 g (20 g NaOH/100 g rice hull) with apparent dry-matter digestibility values for the hulls of 20%, 41% and 51% respectively.

The energy cost of nesting activity and oviposition of hens in different environments has been determined.

The oxygen consumption of hens on a wire floor reached a peak during the last 15 min before oviposition. However, the oxygen uptake of hens accustomed to a litter floor had fallen to a minimum at this time.

The energy cost of expelling the egg is minimal. There is a good correlation between the locomotor activity and the heat production.

The variations in heat production and body temperature on different types of floors are explicable by the differences in nesting activity.

Merino sheep were given abomasal infusions of (i) zein (80 g/day), (ii) zein (80 g/day) supplemented with L-lysine (6 g/day), L-tryptophan (1 g/day) or lysine and tryptophan together, or (iii) L-leucine (20 g/day). Effects on wool growth (length growth rate, fibre diameter, fibre volume growth rate and mass of wool grown) and on plasma amino acids were measured.

Zein increased length growth rate and decreased fibre diameter; on average the volume growth rate and mass of wool grown were not significantly altered. The addition of tryptophan to the infusion of zein did not significantly alter wool growth, whereas the addition of lysine significantly increased all aspects of wool growth. The responses to these treatments were rapid and were adequately assessed during 12-day infusion periods. The infusion of leucine did not cause any appreciable changes in wool growth.

Leucine supplementation increased the concentration of leucine in blood plasma about six-fold. Zein decreased the concentration of lysine and ornithine in plasma and increased the concentration of several essential amino acids; leucine was increased about seven-fold. The addition of tryptophan to zein had no effects on plasma amino acids, whereas lysine decreased the concentration of several amino acids in plasma and markedly increased lysine.

Thirty-four (13♂, 21♀) entire cross-bred lambs were suckled on reconstituted, spray-dried cows' milk from 2 days of age for varying periods of time up to 18 weeks before being weaned on to solid food or slaughtered to determine chemical composition. The body composition of each sheep (water, fat, protein, energy) was also estimated from the tritiated water (TOH) space at 3-weekly intervals during milk feeding, at intervals of 5–8 weeks subsequently and at slaughter. Comparison between. TOH estimates and whole body analysis confirmed the accuracy of the previously-derived prediction equations.

The relationship between each of the various body components and body weight for individual sheep during milk feeding was described by a ‘bent’ (non-rectangular) hyperbola. There were no substantial differences between animals in either the position or slope of the lower asymptote nor in the slope of the upper asymptote. There were, however, substantial differences in the point of intersection of the two asymptotes both within and between sexes. The mean intersection points for males and females were 17·7 and 14·4 kg body weight respectively.

Sheep weaned at body weights of 11–16 kg subsequently followed the previously defined pattern of growth. Weaning at higher body weights (21–34 kg, body fat not less than 5·5 kg) resulted initially in both fat and/or body weight loss. In the final fattening phase of growth early- and late-weaned sheep of the same sex had similar body composition but females were fatter than males.

Fraction 1 protein (18S) can be isolated in large quantities (order 100 g) in a soluble state by heating lucerne juice, adjusted to pH 6·7 to 6·9, from a Pirie extractor to 63 °C for 10 min. Low speed oentrifugation (2500 g) removed coagulated chloroplast fragments and most of the heat-denatured Fraction 2 proteins. Fraction 1 (18S) protein (> 95% pure) was purified from low molecular weight materials (sugars, phenolics etc.) by ammonium sulphate fractionation and gel filtration on Sephadex G-75 gels.

In each of two experiments two potato varieties were grown at a range of plant densities in order to provide mature tubers of different sizes for the study of the relationshipsbetween tuber size and tuber concentration of nitrogen (N), phosphorus (P) and potassium (K). As tuber size increased, the concentrations of tuber nutrients (g/100 g dry matter) declined to a minimum value and then tended to increase with a further increase in tuber size. This suggests that when tuber samples are taken for the determination of tuber nutrient concentration on a dry-weight basis the sampling procedure should ensure that results do not vary because of differences in the tuber size distribution.

Four groups of eight lambs, 4 months of age and reared parasite-free from birth, were used to investigate the effect of the intestinal parasite Trichostrongylus colubriformis on the intake and efficiency of utilization of food, using balance trial and comparative slaughter techniques. One group (CI) was killed initially as control. Two further groups (ALC and ALI) were offered ad libitum a complete ruminant diet. The ALI group was dosed orally each day for 14 weeks with 2500 infective larvae. Sheep in a further group (PF) were individually paired to members of the ALI group, and given the same amount of food as their pair. Balances of nitrogen, Ca and P and the digestibility of dry matter and energy were determined for the ALI and PF groups during weeks 6–7 and 12–13 and after 98 days of infection the sheep were killed. The bodies of these and the CI and ALC sheep were analysed for water, fat, nitrogen, Ca and P contents.

Parasitism reduced food intake over the whole experiment by 9%, but had no effect on the digestibility of energy or nitrogen. At the first trial the N balances of the ALI group were inferior to those of the PF group due to increased urinary N excretion, but there was no difference at the second trial. Ca and P balances of the ALI group tended to be inferior to those of the PF group at both trials. The weight gain of the ALI sheep was only 50 % of that of the PF sheep with the same digestible energy and protein intakes. The protein content of the gain in empty body weight of the ALI sheep was 80 g/kg compared with 112 and 124g/kg in the ALC and PF groups, respectively. Possible causes of the poor protein anabolism are discussed.

The gross efficiency of utilization of metabolizable energy for growth was calculated to be 13·3 % in the ALI sheep, compared with 26·2 and 24·2 % respectively, in the ALC and PF groups. It was not possible to determine whether this was due to change in maintenance requirement or in efficiency of fattening.

The Ca and P content of the skeletons of the ALC and PF sheep increased by 55 % during the 98-day period, while no net change occurred in the ALI sheep. It was concluded that this was caused by an induced mineral deficiency resulting from parasitic damage in the small intestine.

Results of a 13-week group feeding study (Expt 1) and a 16-day digestion and mineral, nitrogen and water balance study (Expt 2) in which alkali-treated rice hulls were fed to young Border-Leicester × Merino sheep of 24-kg body weight are reported.

Five pelletized diets comprising a 1:1 mixture of ground lucerne and alkali-treated ground rice hulls (Expt 1) or these five diets supplemented with biuret plus one diet of 100% lucerne pellet (Expt 2) were examined.

Sodium hydroxide at levels of 0, 2·5, 5, 10 and 15% (w/w) was applied to rice hulls for 12 h and neutralized with acid. Sheep fed the 5% NaOH treatment level or greater maintained or increased body weight: those fed the 0 and 2·5% level lost body weight. Daily food organic matter intakes were: 5% alkali, 1025 g, 0% alkali, 765 g; 100% lucerne, 1195 g.

Organic matter digestibility was highest (52%) for the diet containing rice hulls treated at the 15% alkali level and this digestion coefficient was significantly greater (P < 0·05) than for the control diet (nil alkali) (42%) but not significantly greater than for diets with 2·5, 5 and 10% levels of alkali.

It'is indicated that cell wall organic matter of rice hulls treated with 15% alkali was digested to an extent of 62% whereas cell wall organic matter in the control diet (0% alkali) was digested to an extent of 13%.

Cellulose digestion (52%) of the rice hull component of diets was not increased by alkali treatment suggesting the alkali to have freed hemicellulose components of the cell wall for digestive attack. Digestibility of lignin of the rice hull component of diets was not significantly increased by alkali treatment.

Animals tolerated the salt contents of diets containing rice hulls treated at high levels of alkali, were able to clear the excess salt from their bodies without significant alteration of their blood haematocrit ratios, and drank significantly more water. All sheep fed diets containing rice hulls had appreciable amounts of soluble silica in their blood plasma (> 100/μg/l) and urine (> 25 μg/l).

It is concluded that alkali beneficiation of rice hulls offers a means of enhancing their nutrient worth to ruminants and that the process requires further study.

In laboratory tests tri-n-butyl phosphate applied by spraying as an emulsion at a rate equivalent to 0·25% of leaf fresh weight doubled the drying rate of individual S.24 perennial ryegrass leaves measured at 28 °C, relative humidity 22% and air speed 40 cm/sec. Increasing the rate of application produced no further increase in drying rate. In other experiments the same rate of application stopped respiration of leaves and no resumption of respiration was found in the subsequent 4 days. Comparisons of the dry-matter contents of leaves when removed from the plant and after being allowed to dry for 1 week at 27 °C and relative humidity 80%, indicated that inhibition of respiration resulted in large reductions in dry-matter losses. The potential value of a chemical spray which will both increase drying rate and reduce respiration as an aidto the field drying of grass crops is discussed. While it would be incautious to extrapolate from laboratory tests on single leaves to the field situation, evaluation under more practical conditions is clearly warranted.

The F1 and F2 generations of a diallel cross of six-row barley involving the parents, Beecher, Athenais, Atlas 46, 3130-4564-3, and 3130-864-4 were studied and heterosis, inbreeding depression, and combining abilities were measured for grain yield, number of tillers per plant, number of kernels per plant, kernel weight, and plant height. Significant heterosis was detected for grain yield in two of the ten crosses, for number of tillers per plant in one cross, for number of kernels per plant in two crosses, for plant height in three crosses, and for kernel weight in none of the crosses. The inbreeding depression of the F2 generation was present in most cases but significantly so in a few. Atlas 46 x 3130-4564-3 exhibited inbreeding depression for grain yield, number of kernels per plant, and plant height.

The general combining ability (GCA) mean squares of both generations were significant for all characters studied except number of kernels per plant in the F1 generation. The specific combining ability (SCA) mean squares were significant for only plant height in the F1 generation and all characters studied except number of tillers per plant in the F2 generation.

The GCA effects indicated that Beecher and Athenais are good general combiners for grain yield and its components. The latter parent produced good yielding hybrids with slightly shorter plants than the remaining hybrids.

The SCA effects revealed that Athenais × 3130-4564-3, Athenais × 3130-864-4, and Beecher × Atlas 46 seem good specific combinations for high grain yield. Also, the former two crosses tend to produce shorter plants.

A laboratory and glasshouse study investigated whether it was possible to improve the availability of magnesium from calcined magnesite (MgO). Samples varying from largely unchanged magnesite (MgCO3) to overburnt MgO were made by calcining small quantities of magnesite ore for up to 6 h at several temperatures between 500 and 1000 °C in the laboratory. The effect of calcining conditions on weight loss on ignition, particle size distribution, total, water-soluble and NH4+ -exchangeable Mg was determined and results compared with the current commercial oxide and kieserite (MgSO4. H2O).

The results indicated that an oxide could be produced containing nearly double the amount of readily-exchangeable Mg of the oxide used at present. The analysis showed that the most reactive oxide was produced either by burning for 3 h at 700 °C or about half-an-hour at 800 °C, i.e. the minimum time at each temperature for complete conversion of the carbonate to the oxide. Either of these two oxides increased the Mg in plants of the three crops grown in the glasshouse by 0·3% on average, whereas plants given the commercial oxide increased it by only 0·2%. The three crops removed about 70% of the applied Mg from the most reactive oxides but only 50% of the Mg from the commercial oxide. The results of an incubation experiment suggested that burning at 700 °C for 3 h gave a marginally more reactive oxide than the short burn at 800 °C. However, the most reactive oxide produced supplied magnesium at a slower rate than kieserite. This may not necessarily be a disadvantage since most of the soils where Mg deficiency of sugar beet and similar crops is a potential problem need a Mg fertilizer which maintains or gradually increases soil Mg. Thus the improved oxide may bo suitable and a comparison in field experiments of the effects of kieserite and oxides produced under different calcining conditions is needed.

Pot experiments in which cowpea and hyacinth bean were grown at 15–45% soil moisture showed that nodulation, nitrogen fixation and plant growth were poor at 15%. The weights of nodules and plants were lower in January (winter) than in June (summer). In June cowpea was more tolerant of dry conditions giving good nodulation at 25–35% whereas hyacinth bean required 35–45%.

Under field conditions the number and dry weight of nodules were affected by the irrigation interval whereas plant growth was affected by the amount of water applied. Applying 75 mm depth of water every 7 days gave the best combination of nodulation and plant growth.

The seed-coat of all white-flowered varieties of Vicia faba and segregants tested was free of tannin. In two field trials, the whole grain of white-flowered varieties wassignificantly higher in in vitro digestibility of the dry matter, on average 4·7% higher, than coloured-flowered varieties of similar seed size. In subsequent trials where the testa and cotyledon were examined separately, this difference was shown to be largely due to a mean D value (digestibility of the organic matter) of the testa in tannin-free varieties of 56·4% compared with 17·2% in tannin-containing varieties. Seed size was positively correlated with D value but not because of differing proportions of testa.

Differences between varieties in acid-pepsin solubility and protein content of the testa were much smaller and not associated with presence of tannin. The testa colour of some tannin-free F2 plants was a darker shade of grey than either parental population. An inbred line completely lacking in anthocyanin in flowers and stem but with the normal black wing spot had tannin in its testa.

Grains of peas from the coloured-flowered variety, Minerva, reacted to a tannin test wheieas those from white-flowered varieties, Greenshaft and Flavanda, did not.

The case for breeding further tannin-free varieties of Vicia faba is discussed.

Untimely ploughing and rotavation of a silt loam soil was found to increase bulk density, and mechanical resistance to a needle penetrometer probe, and to reduce air porosity. These effects were not found deeper than 8 cm, although measurements with a 13 mm field penetrometer probe indicated some increase in mechanical resistance down to 30 cm. The effect of untimely cultivations on soil conditions was small when compared with the effect of loosening by hand digging. This treatment reduced substantially the bulk density and mechanical resistance; it increased air porosity and moisture content of the subsoil. Although measurements of mechanical resistance with the laboratory penetrometer were 2·4 times those of the field penetrometer, there was nevertheless good correlation between measurements.

Two experiments designed to compare lambs born to Merino ewes subjected to either nutritional deprivation or high ambient temperatures (diurnal: 8 h at 42·2 °C, 16 h at 32·2 °C) during the last two thirds of gestation are described.

In Expt 1, lambs from ewes group-fed to maintain maternal body weight at high ambient temperature were lighter (P < 0·01) and had shorter metacarpal bones (P < 0·01) than those from ewes fed to either lose, maintain or gain weight at prevailing temperatures (– 2·0 °C to + 16·4 °C). The regression of metacarpal length on the cube-root of birth weight (‘linear equivalence’) was linear. Simple maternal under-nutrition was thus not indicated as a cause of foetal stunting in heat-stressed ewes, though the proportions of affected lambs closely resembled those of the nutritional dwarfs.

In Expt 2, in which all ewes were individually fed, heat-stressed ewes fed ad libitum consumed 40% less feed and produced lambs which were markedly lighter than those from controls at prevailing temperatures. Other control ewes pair-fed at the level of intake of heat-stressed ewes gave birth to lambs of similar weight to those fed ad libitum. Thus, although feed intake was substantially reduced at high temperatures, the amounts actually eaten by heat-stressed ewes were sufficient to enable control ewes to produce lambs of normal weight. The relationships between birth weight and the weight of the adrenals, cerebellum, cerebrum, heart, kidneys, liver, spleen and thyroid were linear, irrespective of treatment, and as in Expt 1 metacarpal length was linearly related to the linear equivalence of birth weight. However, not all changes in body components were directly proportional to changes in the body as a whole, and heat-affected lambs were thus neither true miniatures nor achondroplastic dwarfs. Until these relationships are clarified it is suggested that ‘stunting’ is the most appropriate description of the influence of high ambient temperature on the sheep foetus.

The findings are consistent with the suggestion that the adverse effects of high temperature arise from an extreme form of foetal undernutrition.

Hotroom treatment of ewes during the last two-thirds of gestation resulted in the birth of lambs which were significantly lighter than lambs born to nutritionallydeprived ewes. Neither high temperature nor undernutrition had significant effect on the density of either primary or immature secondary wool follicles, but the total number of mature secondary follicles tended to decline in the lambs from unheated ewes as the level of nutrition declined, and was significantly reduced by a further 30 % in the hotroom group.

In a second experiment, heated and unheated ewes fed to appetite were compared with unheated ewes pair-fed to the hotroom level of feed intake. High temperature had no apparent effect on maternal wool growth, but did reduce total wool follicle number in new-born lambs by approximately 50%. This effect was most marked with respect to mature secondary follicles (only 18% of unheated mean), less so in immature secondaries (56% of unheated mean), and barely discernible amongst primary follicles (93% of unheated mean). None of the differences in follicle numbers between the two unheated groups was significant.

The results suggest that the effects of high temperature on wool follicle development in the sheep foetus are akin to those of extreme undernutrition.

Thirty-eight mature Scottish Blackface sheep were mated at pasture and 32 brought indoors when 3–4 weeks pregnant. Eight were killed at this stage as controls (CI). The remaining 24 were offered a basal hay ration (200 g/head/day) supplemented with a semi-purified diet containing 84 g crude protein/kg and either 1·5 (P1), 2·8 (P2) or 9·3 (P3) g P/kg dry matter. The rate of feeding of the supplement allowed a mean daily P intake (g/day) in groups P1, P2 and P3 of 1·1, 1·6 and 4·7 and 1·6, 2·5 and 7·9 during weeks 4–15 and 16–21 of pregnancy, respectively. Six well-nourished sheep, fed conventionally, provided control ewes and lambs.

Balance trials were conducted on four sheep from each of groups P1 P2 and P3 during weeks 9–10, 14–15 and 19–20 of pregnancy. All sheep were slaughtered at parturition and selected bones of ewes and lambs removed for histological and chemical examinations. Whole body fat, nitrogen, Ca and P contents of the ewes and mineral content of the lambs were determined.

The faecal P excretion of the P1 sheep ranged from 10·8 to 19·1 mg/kg body weight/ day; urinary P excretion ranged from 0·7 to 2·9 mg/kg body weight/day in early and mid-pregnancy and from 1·0 to 8·1 mg/kg body weight/day in late pregnancy. It is suggested that on this evidence the minimum net faecal and urinary endogenous P loss can be no greater than about 13·5 mg/kg body weight/day. Carcass analysis and bone histology and chemical composition confirmed that the P requirement of pregnant ewes is much smaller than has been generally assumed.

It is suggested that for a 50-kg ewe carrying twins the P requirement increases from an average of 1·1 g/day during the first to about 2·5 g/day during the last month of pregnancy.

Twenty-two beef cows, producing on average 5·5 kg 4% fat corrected milk per day, were offered diets of rolled barley and silage such that eight animals were consuming 70%, seven 95% and seven 120% of their estimated energy requirements. Blood samples were taken at intervals during the day and the plasma concentrations of glucose, free fatty acids (FFA), ketone bodies, total protein, albumin, globulin, urea nitrogen, calcium, inorganic phosphate, magnesium and copper determined.

Diurnal variation was found in the plasma concentration of glucose, FFA, ketone bodies, urea nitrogen, albumin, calcium and magnesium; it was particularly marked for the first four constituents and appeared to be related to feeding.

There were no overall significant differences between groups in the mean daily concentrations of the measures of energy status (glucose, FFA, ketone bodies), but significant (P < 0·001) prefeeding group differences were found in glucose and ketone body concentrations. No significant differences between groups were found for the remaining constituents.

There was a postprandial depression in plasma glucose concentration, which was positively correlated with FFA concentration.