Threonine requirement for broiler males from 42 to 56 days of age

Threonine adequacy was assessed in male broilers from 42 to 56 days of age. A common feeding regimen was given for the first 6 wk. Then six concentrat ions of threonine were fed ranging from 0.50 to 0.80% in progressive increm ents of 0.06%. Growth rate and feed/gain were optimized at approximately 0. 68 and 0.67% dietary threonine, respectively. Threonine needed to maximize relative carcass yield increased to 0.75%, whereas the amount to fully reco ver breast fillet weight and its relative yield was 0.70%. The proportions of abdominal fat and carcass defects were unaltered. The threonine requirem ent to optimize live performance is less than that needed for complete reco very of whole carcass and its breast fillets.