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Revista Brasileira de Zootecnia
On-line version ISSN 1806-9290
HOMEM JUNIOR, Antonio Carlos et al. Sunflower grains or protected fat in high concentrate diets and compensatory gain for feedlot lambs. R. Bras. Zootec. [online]. 2010, vol.39, n.3, pp. 563-571. ISSN 1806-9290. http://dx.doi.org/10.1590/S1516-35982010000300016.
The effects of three diets and two feeding managements were assessed on feedlot lamb performance and carcass. Thirty six lambs with initial 18.7 ± 2.4 kg weight were distributed in a randomized complete block design in a 3 × 2 factorial arrangement and were fed a free-lipid diet, and a sunflower grains-added diet or a protected fat-added diet. Six lambs on each diet were submitted to feeding restriction management and later compensatory gain, while the other half was fed ad libitum throughout the feedlot period. Dry matter intake, weight gain and feed conversion ratio, urea and blood cholesterol, carcass characteristics and slaughter by-products were evaluated. During realimentation period the intake of lambs that underwent feeding restriction did not differ from the freely-fed animals. It was not affected by the diet but at the end of this period, the accumulated intake was 11.8% smaller for those lambs previously submitted to feeding restriction. Feed intake to slaughter weight was not influenced by the feeding management. In the restriction period, the blood cholesterol levels were 24% higher than those without restriction, but there was no difference during the realimentation period. The lipids in the diets increased the cholesterol blood levels in both the restriction and realimentation periods and reduced urea blood levels during the realimentation period. The performance, evaluated at slaughter weight, was damaged by the restriction management. There were no effects of feeding management or diet on the carcass parameters. Lipid sources increased the total fat proportion and decreased the gastrointestinal tract content. The feeding management with restriction damages weight gain and feed conversion ratio in lambs up to slaughter.
Keywords : carcass; feed restriction; lipid sources; performance; realimentation; sheep.