The objective of this study was to evaluate the influence of feeding energy levels during the last third of gestation and lactation on performance of ewes and lambs up to weaning. The experiment was carried out in the sheep raising sector of Universidade Estadual de Londrina (UEL), from August to December of 2007. Thirty-two adult lambs with 105 days of gestation, average live weight of 57.55 kg and average body condition scores of 3.42 were used in the beginning of the experiment. The animals were confined in collective pens, distributed randomly in three treatments: 2.4; 2.2 and 2.0 Mcal of metabolizable energy (ME)/kg of dry matter (DM). Feed supply was ad libitum during the last third of gestation and lactation. Weaning occurred at 70 days. Body weight, body condition score and milk production of ewes and body weight of the lambs were analyzed. There were no significant differences for body weight and body condition of ewes at lambing; however, the level of 2.4 Mcal enabled better results for those characteristics at weaning and higher gain in weight and body condition scoring during the experiment. Severe energetic restriction (2.0 Mcal ME/kg DM) determined lower average daily milk production. Lambs from levels 2.4 and 2.2 presented similar weights in all measurements and were superior to those in level 2.0. Lambs from level 2.4 presented higher average weight gain from birth to weaning. The energetic restriction upon lambs at the end of gestation and during lactation limits the performance of ewes and lambs up to weaning.

Avaliaram-se as características quantitativas e a composição regional e tecidual de carcaças de cordeiros submetidos a três níveis de energia (2,23; 2,54 ou 2,85 Mcal de energia metabolizável/kg MS) na alimentação e abatidos aos 32,2 ± 3,8 kg de peso corporal e 145,6 ± 20,1 dias de idade. As rações eram isoproteicas (16,70% PB) e foram fornecidas a 18 cordeiros não-castrados, mestiços Texel, confinados em baias individuais em aprisco com piso elevado do solo e ripado. As meias-carcaças esquerdas foram separadas em paleta, perna, lombo, costelas e pescoço e, em cada um desses cortes, foi avaliada a composição tecidual (osso, músculo e gordura). Com exceção da porcentagem de lombo, os níveis de energia apresentaram efeito quadrático sobre os demais cortes. Com o nível intermediário de energia, foram obtidas as maiores porcentagens de paleta e pescoço e os menores valores de perna e costelas. O nível energético da dieta influenciou a distribuição dos cortes na carcaça, mas não afetou sua composição tecidual média. A paleta foi o corte com a maior variação tecidual decorrente dos níveis de energia. Os cortes analisados podem ser usados para estimar a composição tecidual média das carcaças, no entanto, a paleta é o menos indicado.

The objective of this study was to evaluate quantitative characteristics and carcass regional and tissue composition of lambs submitted to different energy levels (2.23, 2.54 and 2.85 Mcal ME/kg DM) in the diet and slaughtered with 32.2 ± 3.8 kg body weight and at average age of 145.6 ± 20.1 days. The diets were isoproteic (16.70% CP) and fed to 18 no castrated crossbred Texel male lambs. The lambs were confined in individual pens, in a slotted floor sheep barn. The half left-side carcasses were splitted into the shoulder, leg, loin, ribs and neck. The tissue composition (bone, muscle and fat) was also evaluated in each cut. Except for loin percentage, energy levels presented a quadratic effect on the other cuts. The percentages of shoulder and neck were greatest at the middle energy level and the percentages of leg and ribs were lowest at this level. The energy level of the diet influenced the distribution of the cuts in the carcass, but it did not affect the average tissue composition of the carcass. The shoulder was the cut with the greatest tissue variation. The different cuts can be used to predict the average tissue composition of the carcass but the shoulder is the least indicated.