Body composition changes and energy retention in milk-fed lambs undergoingenergy restriction

Eighteen milk-fed Churra lambs were used to study the effect of three level s of energy intake below maintenance requirements (293, 377 and 460 M GE/kg body weight (BW)(0.75)) at different BW (LW: 5 kg; HW: 8 kg) on energy ret ention (ER) and mobilisation of body components. Losses of fat and energy w ere related to energy intake (linear orthogonal contrast; p<0.05). Energy a nd fat mobilisation were greater for HW (linear contrast, p<0.05). There wa s also a significant effect of energy intake on protein retention, with inc reased protein deposition at higher energy intakes (linear contrast, p<0.05 ). Crude protein retention for the LW group ranged from negative (for the l owest level of energy intake) to positive mean values, while the mean value s for the HW group were always greater and positive. No evidence of mainten ance energy requirements changing quantitatively during the milk-fed phase was found in this study. Daily NE requirements for maintenance were not sig nificantly different (p>0.05) for LW and HW groups either, the overall valu e being 494 kJ/kg BW0.75 (SE 74.4). (C) 1999 Elsevier Science B.V. All righ ts reserved.