Efeito da Suplementação de Metionina Sobre o Desempenho e a Avaliação de Carcaças de Frangos de Corte Effect of Methionine Supplementation on Performance and Carcass Yield of Broiler Chickens

Um experimento foi conduzido para avaliar os efeitos da suplementação de metionina em dietas de crescimento (22 a 42 dias de idade) sobre o desempenho, rendimento e composição química da carcaça de frangos de corte. Foram utilizados 2000 frangos de corte da linhagem comercial Ross, sexados, distribuídos em um delineamento ao acaso, em esquema fatorial 2 x 5 (sexo e níveis de metionina) com quatro repetições de 50 aves cada. As dietas foram formuladas para conter 100% ,110%, 120%, 130% e 140% dos níveis de metionina recomendados pelo NRC (1994). Aos 42 dias de idade, as aves foram abatidas para avaliar a quantidade de gordura abdominal, bem como o rendimento e a composição química da carcaça. Ao aumentar o nível de metionina da dieta, não houve efeito (p> 0,05) sobre o ganho de peso, consumo de ração, conversão alimentar, mortalidade, gordura abdominal, e rendimento de carcaça, bem como, umidade, proteína, gordura e cinzas do peito e pernas. Não foi verificado efeito (p>0,05) de interação entre nível de metionina e sexo, mas as fêmeas apresentaram maior percentual de gordura abdominal (p<0,05) que os machos. Como o nível de metionina não afetou o desempenho, rendimento e composição química da carcaça, concluiu-se que a recomendação sugerida pelo NRC (1994) de 0,38% para frangos de corte no período de 22 a 42 dias de idade está adequada.<br>One experiment was conducted to evaluate the effect of dietary additional methionine levels during the grower period (22 a 42 days of age) on performance, carcass yield, and chemical composition of broiler chickens. Two thousand sexed Ross broilers, were reared in a randomized factorial 2 x 5 design (sex and methionine levels) with four replications of 50 birds each. Experimental diets were formulated to contain 100%, 110%, 120%, 130% and 140% of methinine level suggested by NRC (1994). Methionine levels were, .38, .42, .46. .50 and .54%, respectively. At 42 days of age birds were slaughtered to evaluate carcass yield, abdominal fat and chemical composition. Increasing methionine level did not affect (p>.05) weight gain, feed consumption, feed conversion, mortality, abdominal fat, and carcass yield and breast and thigh moisture, protein,fat and ash.. Interaction between methionine level and sex was not significant (p>.05), but females presented higher abdominal fat (p<.05) than males. As methionine level did not affected performance and carcass yield and composition, it was concluded that the methionine level during grower period (22 to 42 days of age) suggested by NRC (1994) is adequate

Evaluation of strain, dietary energy level and stocking density on broiler feathering

This study evaluated the effects of strain, stocking density and dietary energy level on the feathering of broiler chickens. Four trials were carried out between September 2000 and April 2002. There were 10,685 broiler chicks from the strains Ross 308, Cobb 500, Hybro PG, Hubbard, MPK, and Isa Vedette. The bids were reared at stocking densities varying between 10 and 16 birds/m² and were given diets containing different metabolizable energy levels. Broiler feathering was evaluated either by atrributing scores from 1 to 10 to feather covering along the thigh and back (visual inspection), or by determining the percentage weight of the feathers at 28 and 42 days of age. Increasing rearing densities resulted in poorer feathering, mainly if 12 or 13 birds/m² were compared with 16 birds/m². The strains showed different feathering; it was better in Cobb 500 and MPK birds, whereas Hubbard birds showed poorer feathering, mostly along the back. The energy level in the diet has also affected feathering scores. Medium energy level resulted in better feathering along the back at 28 days, and the low level, in better feathering along the thigh at 35 days of age. Finally, feather scores were better in females than in males