Male and female broiler responses to low and adequate dietary threonine onnitrogen and energy balance

This study evaluated nitrogen and energy utilization by male and female bro ilers that were at 46 and 54 d of age fed diets deficient or adequate in th reonine. Birds were reared in floor pens of an open-sided house and were pr ovided diets that met NRC (1994) nutrient recommendations from placement un til 6 wk of age. At 42 d, 48 birds (24 per sex) were selected and individua lly penned in Petersime batteries and were given feeds that were formulated to contain 0.52 or 0.74% total threonine having 18% CP and 3,200 kcal ME/k g. Two 24-h excreta collection periods were conducted on Days 46 and 54 to assess nitrogen and energy recovery. Males receiving adequate threonine had an advantage in retention of nitrogen and recovery of AME(n) over males co nsuming the low threonine diet. Utilization of nitrogen by females was simi lar at both threonine concentrations, and AME(n) corresponded to the concen tration recovered by males when threonine was adequate. Inadequate threonin e appears to create conditions that reduce recovery of energy by male broil ers.