GROWTH AND DEVELOPMENT IN BEEF-CATTLE .2. DIRECT AND RESIDUAL EFFECTSOF PLANE OF NUTRITION DURING EARLY-LIFE ON THE CHEMICAL-COMPOSITION OF BODY COMPONENTS

Low, medium and high planes of nutrition were imposed on Friesian calv es from 1 to 13 weeks of age (Period 1) and factorially arranged with low and high planes of nutrition in the 13-25 week period (Period 2). In the final (residual) period, from 25 weeks to slaughter, all animal s were given the same high plane diet. The different planes of nutriti on were achieved by offering restricted allowances of milk replacer or concentrates with roughage ad libitum. The roughage was grass hay dur ing the milkfeeding period and grass silage thereafter. Representative animals were slaughtered at 1, 13 and 25 weeks of age while the remai ning animals were slaughtered at mean liveweights of 503 and 553 kg. T he ME intake of the low plane animals in Period 1 was 0.55 that of the high plane animals and produced daily accretions of protein, fat and energy in empty body which were respectively 0.43, 0.29 of the high pl ane and daily accretions of protein, fat and energy in empty body were 0.46, 0.59 and 0.54 of the gains of the high plane animals. Within Pe riod 2 compensatory protein growth was obsereved in both carcass and n on-carcass components in response to nutritional restriction in Period 1. Compensatory protein growth was also obtained in the carcass compo nent in the residual period as an indirect effect of nutritional restr iction in Period 2. Nutritional restriction in early life produced rel atively small non-significant direct effects on body and carcass compo sition and while early restriction subsequent produced a considerable degree of compensatory growth, there were no significant differences i n carcass measurements or chemical composition of the carcass by the f inal slaughter weight.