ANIMAL PERFORMANCE AND CHEMICAL BODY-COMPOSITION OF LAMBS FED DIETS WITH DIFFERENT PROTEIN SUPPLEMENTS

Thirty six Merino lambs with average initial live weight of 13.5 kg (S E +/- 0.56 kg) were used in a 3 x 3 factorial arrangement (4 lambs per group). The treatments were three concentrate supplements (barley [B] , barley 82.5% plus soybean meal 14.5% [BSM] and barley 82.5% plus mea t meal 14.5% [BMM]) and three slaughter weights (20, 25 and 30 kg live weight). The lambs fed the B diet consumed less concentrate supplemen t (0.701 vs. 0.780b and 0.758b kg DM day(-1) P < 0.05) gained weight l ess rapidly (217 vs. 304b and 304b g day(-1), P < 0.01) and had a grea ter food conversion ratio (3.29 vs. 2.64b and 2.57b g DM supplement kg (-1) LW gain, P < 0.01) than the lambs on the BSM and BMM treatments r espectively. Lambs supplemented with B were characterised by the highe st fat and energy deposition (P < 0.01) in both components of the empt y body weight (carcass and 'non-carcass'). Although diet protein conce ntrations were different between supplements (B: 165.5, BSM: 219.3 and BMM: 237.2 g kg(-1) DM), there were no differences(P > 0.05) in crude protein intake between BSM and BMM. (171.0 vs. 179.7 g crude protein day(-1)). The source of dietary protein (soybean meal vs. meat meal) d id not have a significant influence (P > 0.05) on performance and chem ical body composition of lambs. The interactions between the effect of slaughter weight and the concentrate supplement were non-significant (P > 0.05). This study suggests that meat meal can successfully replac e soybean meal as a protein supplement for growing lambs from weaning to 30 kg live weight and offer an alternative to soybean meal as a reg ional protein source for lamb diets. (C) 1998 Elsevier Science B.V. Al l rights reserved.