The effect of dl-methionine and betaine on growth performance and carcass characteristics in broilers

An experiment was conducted to determine if betaine could replace methionine in a methionine deficient diet. In order to avoid the effects of betaine as methyl group donor or as osmoprotectant or coccidiostat enhancer, sufficient amounts of methyl donating compounds were added and clean conditions were used to reduce the coccidiosis challenge. l of 576 day-old female broiler chicks were fed one of six diets in a 3 (0, 0.6, 1.2 g/kg of dl-methionine)×2(0 and 0.5 g/kg of betaine) factorial arrangement between 0 and 41 days. The basal diet contained 3.2 g/kg (0–21 days), 2.8 g/kg (21–38 days) and 2.5 g/kg (38–41 days), of methionine, respectively; 3.4 g/kg (0–21 days), 3.6 g/kg (21–38 days) and 3.5 g/kg (38–41 days) of cystine. There were eight replicates of 12 birds per treatment. Performance was determined at 21 and 41 days. At the end, carcass and breast yields were determined on nine chickens per replicate, and abdominal fat on three chickens per replicate. were no significant interactions between betaine and dl-methionine. dl-methionine improved (P<0.001) body weight and feed to gain at 21 and 41 days whereas the effects of betaine were relatively small and not significant (P>0.10). Breast yield increased at all levels of dl-methionine addition (P<0.001), while betaine increased carcass yield (P<0.05). These results suggest that betaine does not replace methionine in its function as essential amino acid in protein metabolism, but may improve carcass yield.