Effect of diet on growth and plasma ascorbic acid in chicks

Factors affecting ascorbic acid (AsA) biosynthesis in chickens. II. Effect of dietary AsA and strain of chicken

The present study examined the effect of supplemental ascorbic acid (AsA) and ascertained if genotype is a determinant of biosynthesis and the response of strains to dietary AsA. Slow- (Ottawa Meat Control; OMC) and fast-growing (Peterson Enhanced x Hubbard; PEH) chicks were fed 1000 mg/kg AsA from 1 to 10 weeks of age. The activity of l-gulonolactone oxidase (GLO) was used to measure biosynthesis and estimated synthetic capacity (ESC) computed. Body weight was not affected by diets and relative kidney weight decreased with age. In 1 week, dietary AsA increased plasma AsA and inhibited GLO activity with a greater reduction in OMC birds. At 10 weeks, GLO activity was depressed almost uniformly in both strains. Strain by age and diet by age interactions were detected for GLO activity and ESC with significantly greater decline in PEH birds and birds fed supplemental AsA. The results demonstrated that dietary AsA inhibited biosynthesis in meat type chickens and the response at 10 weeks was not influenced by growth rate; and the age dependent decline in biosynthesis was more pronounced in the commercial PEH birds. The result suggests that such strains may be compromised in some situations. Research using multiple dietary levels of AsA, commercial strains, and defined stressors is warranted.

Stability of dietary ascorbic acid and the effect of supplementation on reproductive performance of broiler breeder chickens

1. The purpose of the study was to determine the stability of dietary ascorbic acid and the reproductive responses of broiler breeder chickens to supplemental 75 mg ascorbic acid/kg diet. 2. Six breeder flocks of 13,000 birds each were studied. Egg production, eggshell porosity, fertility, hatchability and plasma ascorbic acid were measured. 3. Storage of the diets under dry heat resulted in a linear decrease in ascorbic acid content and the rate of decline was 5-fold higher in the supplemented diet. 4. Differences were not detected between treatments in egg production, egg weight, eggshell porosity, fertility, hatchability or plasma ascorbic acid. 5. The results did not provide evidence of a beneficial reproductive response to the inclusion of ascorbic acid in commercial broiler breeder diets.

Nutrição Pós-Eclosão de Frangos de Corte

A emergência da casca marca o final do período de incubação das aves. Esse período pode ter extremos que vão de 480 a 510 horas em galinhas domésticas. As aves precociais nascem com reservas nutricionais provenientes do albúmen e gema residuais contidos no saco vitelino, que são importantes nas primeiras horas de vida enquanto ocorre a adaptação à alimentação independente, com recursos obtidos no meio ambiente. Aparentemente, os pintainhos de corte não apresentam restrições significativas com relação à utilização dos nutrientes obtidos externamente. Uma exceção, de importância questionável, pode ser a possível redução na capacidade de emulsificação das gorduras devido a uma menor concentração de sais biliares momentaneamente disponíveis. Entretanto, o imediato alojamento com disponibilização de alimento e água acelera a adaptação das aves à vida independente e tem reflexos positivos no desempenho posterior. Atrasos no alojamento, seja ainda na câmara de eclosão, transporte ou manejo dos pintinhos, reduzem o potencial de síntese protéica muscular, especialmente na musculatura do peito. Por muitos anos, os produtores de frangos de corte têm usado programas nutricionais que incluem uma mesma dieta da eclosão até as 3 semanas de idade. Recentemente, tem havido um aumento no interesse comercial por uma dieta especializada que contemple as diferenças de adaptação dos primeiros dias de vida das aves. A existência de diferenças entre exigências nutricionais das aves nessa situação com relação a animais mais maduros é ainda uma incógnita, tendo em vista o volume pequeno de informações disponíveis.