Effects of DL- and L-methionine supplementation on growth performance, carcass quality and relative bioavailability of methionine in broilers fed maize-soybean-based diets

. This experiment was conducted to compare the effects and bioavailability of DL-methionine (DL-Met) and L-methionine (L-Met) supplementation in maize-soybean meal-based diets on performance and carcass of broiler A total of 728-day-old male broilers were divided into 7 groups with 9 replicates (7 replicates of 12, and 2 replicates of 10 chicks) using a 2 × 3 + 1 factorial arrangement in a completely randomised design. Dietary treatments consisted of basal diets (BD) (including 0.619, 0.555 and 0.523% digestible methionine + cysteine (Met + Cys) for starter, grower and finisher pe -riods, respectively) with three levels (0.155, 0.310 and 0.455%) of either DL-Met or L-Met: BD, BD + 0.155% DL-Met, BD + 0.310% DL-Met, + 0.455% DL-Met, BD + 0.155% L-Met, BD + 0.310% L-Met and BD + 0.455% L-Met. The and levels of Met supplementation did overall growth performance, yield of carcass and parts, as as relative internal organ and feather weight. of methionine had no significant effect on overall growth performance, yield of carcass and parts, relative internal organ and feather weight, while methionine growth performance and carcass and cut yields. The slope-ratio assay showed that the relative bioavailability (RBV) of L-methionine to DL-methionine for BW, FCR and BMY of broilers were 123, 91.5 and 88.0%, respectively, i.e. the differences were not significant between the two Met sources. In conclusion, that when DL-Met and L-Met were included in feeds at practi-cal levels, they were equally as a of methionine for broilers.