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Protein and vitamin E levels for broiler breed hens. 2. Effects on yolk and tissue alpha-tocopherol concentration and nitrogen balance

Sixteen broiler breed hens were used with the objective of evaluating the effects of supplementation of two crude protein (14 and 16% CP) and two vitamin E levels (25 and 250mg VE/kg) in the diet on the alpha-tocopherol (AT) concentration in the egg yolk, liver, blood serum and feces, and on the AT and nitrogen (N) retentions. The experiment lasted 25 days, in which 15 days were used for hens adaptation and 10 days for egg and fecal collection for AT and N analyses. The experimental design was a complete randomized design with a 2 × 2 factorial arrangement (CP × VE levels) with four repetitions per treatment. The increasing of VE in the diet resulted in increase (P<0.05) in AT consumption, excretion and retention, reflecting in higher AT concentrations in egg yolk, liver and blood serum (P<0.05). The efficiency of AT retention in birds decreased (P<0.01) at high VE levels, independently of CP levels in diet. The increasing of ten times VE in the diet resulted in lower excretion and in higher retention of N in birds. The increasing of CP levels resulted in more N consumption and excretion in hens (P<0.05), although no difference was accounted for N retention and egg concentration (P>0.05). Thus, it could be concluded that the increasing of VE levels in the diet increased the AT concentrations in the egg yolk and body tissues, and decreased the AT and increased the N retention in broiler breed hens during the laying peak period.

Broiler breed hen; protein; vitamin E; nitrogen balance; alpha-tocopherol

Universidade Federal de Minas Gerais, Escola de Veterinária Caixa Postal 567, 30123-970 Belo Horizonte MG - Brazil, Tel.: (55 31) 3409-2041, Tel.: (55 31) 3409-2042 - Belo Horizonte - MG - Brazil