ALBERT

Description: SummaryForty merino sheep of mixed ages including lambs, ewes, wethers and rams were slaughtered and dissected. The chemical fat content often muscle groups in each sheep was measured directly and the mean value for the musculature of the whole carcass calculated.A characteristic pattern of chemical fat deposition was shown with the intercostal muscle group and the abdominal group being consistently highest in fat content, the shin and hind-limb muscles lowest and other intermediate. The pattern of growth of intramviscular fat was consistent with differences in activity of the muscle groups in the maintenance of posture. It was postulated that variations in fat content in muscle groups are affected by differences in blood flow.A highly significant relationship was established between dry matter and chemical fat content for each of the muscle groups. The regression was characteristic for each muscle group, and differed for most groups.Regressions between individual muscle group fat and that of total musculature fat revealed that no group was consistently the best predictor of the total carcass musculature fat though there was considerable difference between the groups. It was concluded there is no group which could be used for prediction purposes commercially.In a group of 14 other ewes subjected to weight loss up to 30%, and half of which were implanted with resorcylic acid lactone, no discernible effects on muscle group fat content were revealed.

Description: SUMMARYCalves were slaughtered at predetermined weights after being fed individually on fresh and reconstituted whole milk at three levels. The highest level of feeding was ad libitum and the lowest was aimed at keeping the calves at their birth weight for 72 days before providing extra milk to allow growth to proceed.Dressing percentage did not decline with age as it did in a previous experiment using roughage in the diet. The faster-grown calves had a higher dressing percentage. It is concluded that both rate of growth and the physical nature of the diet influenced dressing percentage.Muscle: bone ratio and the amount of fat and bone in the carcass were not significantly affected by the rate of live-weight increase.

Description: SUMMARYThe live-weight gain, efficiency of food conversion, energy and nitrogen accretion as edible carcass, and the forestomaeh development were measured in three groups of calves fed for 10 weeks (days 19–89 of life) either a diet of 4·5 1 of milk daily, or a concentrate meal containing 4% sodium propionate ad libitum, or a concentrate meal ad libitum. All groups had access to lucerne chaff and water ad libitum.The mean live-weight gains of the three groups of calves were 47·5, 36·6 and 37·1 kg respectively even though their total energy and nitrogen intakes were not significantly different. The provision of dietary propionate did not improve the efficiency of food conversion or of energy or nitrogen accretion as the calves ate less of the meal containing propionate and more lucerne chaff. The differences in live-weight gain could be accounted for by the differences in carcass weight. Associated with the higher live-weight gain was a much higher efficiency of food utilization and of edible carcass energy and nitrogen accretion. The superior efficiency of the unweaned calves was concluded to be due to the liquid portion of the diet by-passing the rumeno-reticulum into the abomasum where the efficiency of utilization of highly digestible protein and carbohydrate is greater. The concentrate plus propionate fed calves ate less concentrate but more chaff and had a lower efficiency of food utilization and edible carcass energy accretion than the other weaned group of calves.The weight of rumeno-reticular tissues was greater in the weaned than in the unweaned calves, although the meal plus propionate group ate similar quantities of chaff to the unweaned group. In all groups, the degree of papillary development was related to the intake of concentrates plus roughage. The most appropriate manner to describe ruminal tissue weight is discussed.

Description: SUMMARYThe gross energy and nitrogen contents of muscle, fat, and connective tissue of calves were determined, and from these data and feed analyses the gross energetic (GEE) and nitrogen efficiency (GNE) of growth, and the gross efficiencies of accretion since birth (GEA, GNA) were calculated.The percentage range of actual efficiency values for calves were GEE 55·3–7·7, GEA 18·1–1·4, GNE 58·1–22·8, and GNA 28·1–7·3. Within each treatment group these values were higher in the heavier calves. An hypothesis for the apparent temporary rise in these values in the heavier calves is that a compensatory mechanism acts in calves on low energy and possibly low N intake to enable them better to utilize their food. The results were obtained in calves whose diet was comprised of a reconstituted milk of low-solid content which led to low growth rates.

Description: SummaryThe subcutaneous, intermuscular and cavity fat depots of the half carcasses of 15 Large White × Landrace castrated male pigs, forming a growth series from 8 to 62 kg live weight, were dissected. Seventy individual muscles of these pigs were analysed for intramuscular fat content. The growth rates of each of the four fat depots, relative to total fat, were similar. Subcutaneous fat was the predominant fat depot over the growth range studied. Both intramuscular fat and non-fat dry matter grew faster than the entire muscles containing them. Growth gradients for the intramuscular fat of muscle groups, relative to either total intramuscular fat or to total fat, were similar to those for the entire muscles. The growth gradients for muscle groups were affected by neither the growth of the contained intramuscular fat nor the contained non-fat dry matter. Intramuscular fat density, but not non-fat dry-matter density, varied throughout the carcass. The fat content of muscles was highest in those that could be useful as subcutaneous insulators.