This study was conducted to evaluate the effect of vitamin E and selenium on performance, viability, productive efficiency, and yields of carcass, major cuts, and organs of broilers from 22 to 42 days submitted to cyclic-heat stress. The experimental design was randomized blocks, in a 2 × 3 factorial arrangement with two levels of selenium (0.1 and 0.3 mg/kg) and three levels of vitamin E (300, 400, and 500 mg/kg), plus a control treatment. Animals were submitted to a natural condition of high cyclic temperature. Organic selenium levels of 0.1 and 0.3 mg/kg associated with 300, 400, and 500 mg/kg of vitamin E were tested. The level of vitamin E did not affect the performance or production efficiency of broilers in the period from 22 to 33 days and 22 to 42 days. However, the selenium inclusion level of 0.3 mg/kg improved the viability in both phases. The yields of carcass, major cuts, intestine, and heart were not influenced by the levels of selenium and vitamin E, whereas abdominal fat for the selenium level 0.1 mg/kg decreased linearly with the inclusion in vitamin E.

Bioquímica sérica e carcaça de frangos de corte, em condições naturais de calor, suplementados com zinco orgânico e vitamina E. Serum biochemistry and carcass of broilers, in natural heat conditions, supplemented with organic zinc and vitamin E. ________________________________________________________________________________ ResumoObjetivou-se avaliar o efeito do zinco orgânico e vitamina E nas dietas de frangos de corte expostos a condições naturais de calor cíclico, no período de 1 a 21 dias de idade, sobre o rendimento de carcaça e cortes, resistência da pele e bioquímica sérica. Foram utilizados 600 pintos de corte, machos e fêmeas da linhagem Ross 308, distribuídos em delineamento inteiramente casualizado. Os tratamentos consistiram na inclusão de zinco orgânico em associação a vitamina E nas dietas das aves. O rendimento de carcaça foi maior com a inclusão de 120 mg zinco orgânico/kg quando comparado ao tratamento sem o mineral. Os triglicerídeos séricos foram mais baixos com a suplementação de 300 mg e 600 mg de vitamina E. Houve interação entre os níveis de zinco e vitamina E promovendo a queda dos níveis de albumina sanguínea. O zinco orgânico confere maior rendimento de carcaça e a vitamina E, associada ou não ao zinco, melhora a bioquímica sérica de frangos de corte, em condições naturais de calor cíclico, até os 21 dias de idade. Palavras-chave: aves, mineral, tocoferol, triglicerídeos. AbstractThe objective of this study was to evaluate the effect of organic zinc and vitamin E on diets for broilers exposed to natural cyclic heat conditions, from 1 to 21 days of age, on carcass and cut yield, skin resistance and serum biochemistry. A total of 600 male and female Ross 308 chicks were used and distributed in a completely randomized design in a factorial scheme. The treatments consisted on inclusion of organic zinc (0 and 120 mg/kg) in association with vitamin E (0, 300 and 600 mg/kg) in the birds' diets. The carcass yield was higher with 120 mg of organic zinc/kg when compared to the treatment without the mineral. Serum triglycerides decreased with 300 mg and 600 mg of vitamin E supplementation. There was interaction between the levels of zinc and vitamin E promoting the fall of blood albumin levels. Organic zinc provides higher carcass yield and vitamin E, associated or not with zinc, improves the serum biochemistry of broiler chickens under natural cyclical heat conditions up to 21 days of age.

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