Understanding the functional roles of branched-chain amino acids and their interactions in broiler nutrition and health: a review

SUMMARYThis literature review provides insights into the critical roles and impacts of branched-chain amino acids (BCAA) in broiler chicken nutrition. The unique catabolism of BCAA makes them essential to several metabolic pathways, particularly the mechanistic target of the rapamycin (mTOR) signalling pathway, which is vital for muscle accretion and growth performance. Additionally, BCAA regulate lipid metabolism and intestinal development, alongside other immune and oxidative functions. Further, Val deficiency has been associated with feather and leg abnormalities. Although BCAA requirements are typically based on their ratio to the reference amino acid lysine, an ideal balance among BCAA should be considered in feed formulations due to their shared enzymatic pathways in the initial steps of catabolism, involving branched-chain aminotransferase and branched-chain α-keto acid dehydrogenase. Consequently, antagonism between BCAA may occur, where excessive supplementation of one BCAA, especially leucine, could impair the utilisation of the others, valine, and isoleucine. In summary, the strategic inclusion and balancing of BCAA in poultry diets are vital for optimising growth, health, and efficiency in broiler production. This review provides a comprehensive understanding of BCAA’ roles, emphasising the need for continued research to refine dietary strategies and maximise their benefits in sustainable poultry nutrition.