We completed two floor pen studies to evaluate roles of branched-chain amino acids (BCAA) on growth performance, meat quality, bone quality, and immune responses in two different broiler chicken strains COBB and ROSS. In study 1, we found that imbalance of branched Chain Amino acids (BCAA: Leucine, Isoleucine, and Valine) considerably affect muscle gain, fat formation, gut health, and bone mineralization in broilers. High leucine levels in the diets reduced body weight gain and feed efficiency, and balanced BCAA diets or higher isoleucine and valine diets mitigate negative effects of BCAA imbalance. Furthermore, high Leucine levels significantly affected body composition including bone mineral density & content, lean percent, and fat percent; it significantly increased fat percent but reduced lean percent and bone mineral density & content. For Study 2, we found that imbalance of BCAA significantly affected growth performance, body composition, and bone mineralization in both Cobb and Ross broilers. In addition, Cobb broilers were more sensitive to BCAA imbalance compared to Ross broilers. High leucine significantly reduced growth performance, carcass yield, and bone mineralization, while Valine or Valine & Isoleucine supplementation improved growth performance and bone mineralization. However, Isoleucine supplementation alone seems to reduce growth performance and bone mineralization. High Valine alone mitigate the bone mineralization reduction by high Leucine in Ross, whereas The combination of high Valine and Isoleucine had the highest bone mineral density in Cobb. The current study found that BCAA balance in the diets is critical, and higher leucine in the diets reduced growth performance, meat yield, and bone mineralization in both Cobb and Ross, but higher isoleucine supplementation alone makes the growth depression of higher leucine worse. High leucine and high isoleucine significantly reduce growth, feed efficiency, and meat & bone formation in broilers. Valine is the key amino acid to alleviate the negative effects of high leucine or high leucine & isoleucine combination. The BCAA responses are different depending on the broiler breeds.

Soybean meal based diets are superior than diets containing wheat middlings, Soybean meal diets with Valine supplementation have beneficial effects on overall growth performance, muscle yield and gut health. Cobb birds are more sensitive to BCAA imbalance compared to Ross birds.