No abstract

SUMMARYSteer calves, underfed either from birth to 16 weeks of age, or from 16 to 32 weeks of age, recovered well on refeeding, but only the latter expressed compensatory growth.Carcass characteristics (dressing percentage, carcass length, depth of muscle and fat at the tenth rib, yield and joint distribution of saleable meat, proportions of muscle, fat and bone) of steers underfed in early life were remarkably similar to those of continually grown steers when slaughtered at the same live weight, despite their greater age.Plane of nutrition in early life had no apparent effect on the ultimate eating quality of meat (longissimus dorsi muscle) or on its connective tissue and fat content.

The influence of level of feeding on body composition and carcass characteristics of veal calves was examined.Friesian bull calves, in four groups of nine, were offered reconstituted whole milk at levels of 12%, 15%, and 18% of body weight and to appetite. Only the first group consumed their total allowance. All calves were slaughtered at 15 weeks of age.Body weight tended to increase with feeding level, but the proportions of body parts, relative to body weight, were generally unaffected.A higher feeding level increased the proportions of fat and decreased the proportions of edible meat, water, and protein in the veal carcasses, but group differences were small after adjustment for variation in carcass weight. Feeding level had little or no influence on the proportion of carcass bone or on the chemical composition of the fat-free carcass.Total feed intake was highly correlated with body weight, carcass weight, weight of edible meat, carcass fatness, and carcass energy value.

In an experiment started in June 1976, 14-16-month-old Hereford steers weighing 300 kg were allocated to five treatments. Cattle in four of the treatment groups, viz. high (H), medium (M), low (L) and low-high (L-H) growth rates were held in feedlots and offered whole oats supplemented with linseed meal, hay and minerals to obtain growth rates of 1.0, 0.7, 0.4 and 0.4-1.0 kg day-1 respectively. Steers in the fifth treatment group were grazed on pasture (P) to gain weight at 0.7 kg day-1 and received no supplements. Each treatment group of 10 steers was slaughtered at a mean liveweight of 450 kg. The carcasses of H steers were shorter, had more total fat and a greater depth of fat at the 12-13th rib than those of the L steers (fat depths of H, M and L groups were 10.1, 8.6 and 7.1 mm). The H steers also had a larger eye muscle area, a higher ABCAS (Australian Beef Carcase Appraisal System) score and higher carcass grades than the L steers. The L-H treatment appeared to reduce the fat content of the total side relative to the M treatment but the treatment was confounded with differences in carcass gain and carcass weight. Pasture grazing reduced carcass fat content as compared with grain feeding (15.2 v. 18.6%; P c 0.05), but differences in depth and weight of subcutaneous fat in the carcass side or in individual cuts were not significant. There was no detectable difference in tenderness due to level of feeding or feed type. Separately, the effects of feeding level and grain feeding increased carcass fatness by 16 and 22% respectively; we suggest that these effects are of commercial importance, particularly if the combined effects are additive.

Weaned Friesian steers of 130 kg liveweight were offered a range of supplements from January until May while grazing hay aftermath at 5 steers ha-1. Some of the feeds were also given to similar steers in feedlots. The supplements comprised all combinations of oaten grain, linseed meal and pasture hay. Oats and hay were fed separately and ad libitum and the linseed meal was provided as a daily ration alone or mixed with oats. Above average rains fell in December and January but February and March were dry. The pasture supported an average daily gain of 0.55 kg day-1 during the first five weeks when still green but gains declined and responses to the supplements increased after the pastures dried off and especially after the first autumn rains. For steers grazed on pasture, average daily gains (kg day-1) during the 16 weeks of the experiment were: unsupplemented 0.24, supplemented with linseed meal 0.31, hay 0.43, linseed meal and hay 0.63, oats 0.60, oats and hay 0.73, oats and linseed meal 0.97, oats linseed meal and hay 1.01. For steers in feedlot, gains were : oats 0.12, hay 0.33, oats and hay 0.41, oats linseed meal and hay 0.82. The feed consumption of the steers in the feedlot increased with the protein content of the ration and their liveweight gain was closely related to the amount of food consumed.