Threonine Responses of Cobb Male Finishing Broilers in Differing Environmental Conditions

Abstract

Underfeeding the amino acid Thr may result in suboptimal growth and carcass development, and overfeeding my result in increased diet cost. Adequate knowledge of Thr may be more important in finishing broilers due to increased feed consumption and increased maintenance needs. However, published reports on Thr in the finishing period (d 42 to 56) are few, and recommended requirement estimates vary from 0.60 to 0.75% total Thr. This study was conducted to better understand Thr needs during the 42-to-56-d period in broilers reared in different environmental conditions. Live performance and carcass responses of Cobb male broilers as affected by graduations of Thr were evaluated in clean or dirty floor pen environments. Quadratic responses for live performance and breast meat weight were generated for birds reared in the clean environment and ranged from 0.63 to 0.68% total Thr (0.56 to 0.61% digestible Thr). In contrast, birds reared in the dirty environment responded to Thr in a positive linear manner for live performance and carcass traits. One explanation for birds responding to higher levels of Thr in the dirty environment might have been an increased Thr need for gastrointestinal function.