Growth and development in beef cattle. 1. Direct and residual effects of plane of nutrition during early life on components of gain and food efficiency

Abstract

SUMMARYLow, medium and high planes of nutrition were imposed on Friesian calves 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 animals were given the same high plane diet comprising 3·5 kg of concentrates and grass silage ad libitum. The different planes of nutrition were achieved by offering restricted allowances of milk replacer or concentrates with grass silage ad libitum. Representative animals were slaughtered at 1, 13 and 25 weeks of age while the remaining animals were slaughtered at mean liveweights of 503 and 553 kg. Over 2 years, a total of 120 Friesian steers were taken through to the final slaughter point, with 60 additional animals being slaughtered at interim stages. The animals were housed in non-bedded accommodation throughout the study and the calves were born in January of each year. The ME intake of the low plane animals in Period 1 was 0·55 that of the high plane animals and produced liveweight (LW), empty body (EBW), carcass (CW), non-carcass (NCW) and alimentary tract (ALW) weight gains which were 0·60, 0·46, 0·47, 0·44 and 0·55 of the gains of the high plane animals. In Period 2 the low plane animals had ME intakes which were 0·69 of the high plane animals and produced proportional gains of 0·57, 0·48, 0·45, 0·51 and 0·56 respectively. Previously restricted animals had higher rates of gain subsequently and the indices for weight compensation by the final slaughter point in LW, EBW, CW, NCW and ALW for the low plane treatments in Period 1 were 0·72, 0·82, 0·89, 0·73 and 0·97 while indices for low v. high in Period 2 were 0·82, 0·82, 0·79, 0·86 and 0·95. With lower plane animals, food intakes/liveweight0·75 were significantly higher during the compensating period. Calves which had been restricted in either of the early periods had significantly improved food conversion efficiency during the compensating period but lifetime food efficiency was not affected by plane of nutrition in early life.