Abstract

In Sweden, only fast growing broiler hybrids are available for organic production, and due to the required rearing period of 10-12 weeks growth rate restrictions are needed. Organic feed legislation further complicates the composition of a well balanced diet, which may affect animal health. The experiment comprised 180 Ross 308 broilers divided over 3 dietary treatments; a low crude protein and methionine diet; or a high crude protein diet with similar amino acid levels as used in conventional production, both composed according to organic standards; or the low protein diet supplemented with lysine, methionine and threonine up to levels of the high protein diet; Chickens were immunologically challenged with an inactivated IBDV vaccine, and antibody titres, heterophil/lymphocyte ratios, and lymphoid organ weights were studied. The high protein diet gave the highest live weight and the most efficient FCR. Supplementing the low protein diet with amino acids increased live weight and FCR, even though the effect on FCR at 10 wks was less pronounced. Dietary treatments did not significantly affect any of the immune or stress related parameters measured, indicating that amino acid levels obtained in the organic diets studied are sufficient for the birds to maintain an adequate immune response

Keywords

broiler; organic; protein; methionine; immune responses

Published in

Book title: Full paper in CD-rom version
Publisher: WPSA, France

Conference

XVIth European Symposium on Poultry Nutrition

Authors' information