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

Three isonitrogenous diets with different levels of metabolizable energy (ME; 10.3, 10.9, and 11.5 MJ/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 ± 1.3 kg of initial body weight; BW) supporting single male lambs were penned individually at 24 h 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 (32 kg of BW). Carcasses were then evaluated after 24 h 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 < 0.05). No remarkable changes were observed in carcass traits. We concluded that improving ewe nutrition and consequently the early life nutrition of lambs can really increase profitability of lamb meat production.