Comparison of the absorption kinetics and utilization of crystalline-free and protein-‎bound methionine sources in broilers with single-meal feed consumption

This experiment was performed to compare the absorption kinetics and utilization of different methionine (Met) sources including synthetic-free crystalline DL-Met (DL-Met), L-methionine (L-Met) and dipeptide (Met-Met) and protein-bound methionine (PB-Met) in broilers with single-meal feed consumption. A total of 100 female Ross 308 broiler chickens were fed in a completely randomized design with five experimental diets (basal, DL-Met2.0, L-Met2.0, Met-Met2.0 and PB-Met2.0) in accordance with compliance to the single-meal broiler breeder from 39 to 60 days of age. During experimental period, 90 grams of pellet feed was given per chicken once a day, which was consumed within 17±2.5 minutes. The results showed that dietary supplementation with PB-Met2.0 caused a significant improvement (P<0.01) in growth performance, compared to the consumption of synthetic amino acids. The maximum blood plasma methionine concentration was observed at 1 hour after consumption of diets containing DL-Met2.0 and Met-Met2.0 and 2 hours after consumption of diets containing PB-Met2.0 and L-Met2.0 (P<0.01). The highest carcass protein content and protein utilization efficiency (P<0.01) and also the lowest excreta nitrogen content (P<0.05) were observed in treatment containing PB-Met2.0. The efficacy of essential amino acids, especially methionine was increased in chickens fed diet containig PB-Met (P<0.01). As a result, it seems that DL-Met and Met-Met have less efficiency in broilers with single-meal feed consumption, due to the lack of absorption synchronization with other amino acids. Therefore, the absorption synchronization of methionine using appropriate sources increases its efficiency. In conclusion, PB-Met is recommended as a preferred source of methionine in diet of broilers with single-meal feed consumption.