Responses of fast- and slow-feathering male broilers to dietary threonine during 42 to 56 days of age

Threonine content of feather protein is relatively high, and broilers diffe ring in the rate of feathering may have different dietary threonine needs. This study examined the response of fast and slow-feathering male broilers to feeds either adequate or deficient in threonine. Birds were fed a common feeding regimen from placement until six wk of age. Then a corn-peanut mea l diet containing 0.56% threonine was compared with one having 0.18% of sup plemental L-threonine (0.74% total) until eight wk. Increasing threonine fr om 0.56 to 0.74% improved growth rate with fast-feathered broilers but not slow-feathered broilers. Additional threonine also improved feed/gain; howe ver, birds differing in feathering responded similarly.