Revista Brasileira de Zootecnia
On-line version ISSN 1806-9290
TONETTO, Cleber José et al. Weight gain and carcass characteristics of lambs finished in a natural supplemented pasture, ryegrass pasture (Lolium multiflorum Lam.) and feedlot. R. Bras. Zootec. [online]. 2004, vol.33, n.1, pp. 225-233. ISSN 1806-9290. http://dx.doi.org/10.1590/S1516-35982004000100026.
The objective of this study was to evaluate the performance and carcass characteristics of lambs under three feeding systems. Sixteen lambs, 24 hours after birth, and their mothers were randomly assigned to three treatments: NSP: natural supplemented pasture; RP: ryegrass pasture (Lolium multiflorum lam.) and CON: confinement. Average daily gain of 0.404 kg of RP lambs was higher than the other treatments, whereas NSP animals showed higher gain (0.325 kg/day) than CON animals (0.213 kg/day). The lambs were slaughtered when reached, approximately, 31 kg. The carcass hot weight of NSP animals (15.7 kg) was similar to the RP animals (16.8 kg) and higher than the confinement ones (14.3 kg). NSP, RP and CON animals showed similar results to the cooling index, with values of 2.3 , 2.1 and 2.5%, respectively. Hot carcass yield of NSP (50.2%) and RP (53.7%) animals were similar, however those values were higher than those of CON carcass yield (45.9). Carcass compactness showed no difference between NSP and RP, with values of 0.287 and 0.307, respectively, however, these values were higher than the CON animals (0.253). The carcass of NSP and CON animals did not differ in relation to the fat thickness, with values of 1.6 and 1.0 mm, respectively. These values were lower than the ones obtained from RP (3.3 mm). Average daily gain over 0.4 kg/day and hot carcass yield over 52% can be obtained in lambs fed with their mothers in ryegrass pasture, with slaughter weight round 31kg.
Keywords : average daily gain; compactness; fat thickness; feeding systems; hot carcass yield.