Concentrate levels in the diet for crossbreed Limousin x Nellore bulls: intake, feed:gain ratio and weight gain

Gesualdi Junior, A.; Paulino, M.F.; Valadares Filho, S.C. de; Silva, J.F.C. da; Veloso, C.M.; Cecon, P.R.

Revista Brasileira de Zootecnia 29(5): 1458-1466

2000


ISSN/ISBN: 1516-3598
Accession: 003390921

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Abstract
Forty-five F1 Limousin x Nellore bulls, averaging 14 months of age and initially 330 kg LW, were used to evaluate the effects of different concentrate levels (25.0, 37.5, 50.0, 62.5 and 75.0% on DM basis) and two dietary balance regimes (isonitrogenous or changing protein as dietary energy changes) on the intakes of dry matter and neutral detergent fibre (NDFI), feed:gain ratio (FG), daily gains of liveweight (ALWDG) empty body weight (EBWDG) and carcass weight (CARG). Five animals were slaughtered at the beginning of the experiment as reference, to estimate the initial empty body weight of animals that remained in feedlot. The animals were full fed up to the slaughter weight of 500 kg. Coast-cross grass hay was used as forage source. A completely randomized design in a 2 x 5 factorial arrangement, with four replicates was used. The two dietary regimes resulted in equal animal performance. DM intake showed a quadratic response, and a maximum values of 8.04 kg DM, 1.99% LW, and 89.22 g DM/kg0.75 for the concentrate levels of 41.42, 36.71, and 37.96%, respectively were estimated. The feed:gain ratio, NDFI and days on feed decreased and ALWDG linearly increased as the concentrate levels in the diet increased. ALWDG and CARG showed a quadratic response, with a maximum of 1.16 and 0.81 for 61.11 and 64.47% concentrate in the diet.