Growth performance and carcass traits of early-weaned lambs as affected by the nutritional regimen of lactating ewes

AbstractThree isonitrogenous diets with different levels of metabolizable energy (ME; 10.3, 10.9, and 11.5MJ/kg) were fed to lactating ewes to study the relationships among milk yield and feed intake, growth rate, and carcass traits of early-weaned lambs. Eighteen multiparous Texel×Ile de France ewes (55.7±1.3kg of initial body weight; BW) supporting single male lambs were penned individually at 24h after lambing and evaluated for 42 days. Lambs had free access to a creep feeding system before weaning (42 days of age), and after that they were individually penned and fed a common diet until reaching the slaughter weight (32kg of BW). Carcasses were then evaluated after 24h of refrigeration. Dry matter and ME intake of ewes presented a quadratic relationship with energy level of the diet (P<0.05), and it directly affected milk yield (P<0.01). Milk yield was correlated with DM intake (r=−0.75; P<0.01) and growth rate (r=0.74; P<0.01) of lambs from birth to weaning. On the other hand, in this period there was no relationship between solid feed intake and ADG of lambs (r=−0.05; P>0.05). Therefore, creep feed supplementation was not enough to support a similar growth rate among lambs ingesting different amounts of milk. From weaning to slaughter, DM intake of lambs was greater (P<0.05) for the lambs raised by ewes in the low-energy group, resulting in a worse feed efficiency (P