Glycine, serine, and arginine additions to Cobb 500 female broilers fed dietary variations in crude protein

This study investigated the effects of supplemental Gly, Ser, and Arg on growth performance, carcass traits, footpad dermatitis, and litter ammonia emission of broilers fed low-protein diets from 18 to 42 d of age. A total 576 one-day-old female Cobb 500 broilers were divided into 6 dietary treatments: 1) control, high CP (HCP 20%), 2) medium CP (MCP 18%), 3) low CP (LCP 16%), 4) LCP + 0.20% Gly+Ser, 5) LCP + 0.20% Arg, and 6) LCP + 0.20% Gly+Ser + 0.20% Arg. Although BW gain and feed intake were not affected by treatments, reducing CP to LCP (16% CP) increased FCR regardless of amino acid supplementation, with MCP being intermediate. The calculated net energy values of low CP diets were higher than MCP and MCP. Net energy intake per 1,000 g of gain was also higher for birds fed LCP diets. Protein efficiency ratio was improved for birds fed the LCP diet. LCP diets either with or without supplemental Gly+Ser or Arg resulted in significantly higher relative tender weight. Reducing CP from 20 to 16% significantly increased fat deposition and fat yield. Footpad scores and NH₃ emission significantly decreased on LCP compared to HCP and MCP. Broilers fed reduced CP had good growth, reduced litter ammonia, and improved foot pad health, but increased FCR and peritoneal cavity adipose tissue.