DIETARY THREONINE RESPONSES IN GROWING TURKEY TOMS

A study was conducted to evaluate Thr responses in Large White (Britis h United Turkeys) male turkeys during three time periods: 0 to 31 3 to 6, and 6 to 9 wk of age. The Thr-deficient diets, fed in 3-wk interva ls, were composed primarily of corn, peanut meal, poultry meal,,and so ybean meal as intact protein sources and supplemented with amino acids . Graded levels of L-Thr were added to the Thr-deficient diets. Anothe r group of turkeys received a corn-soybean-poultry meal control diet i n each time period. Diets were formulated to meet a minimum of 110% of suggested amino acid specifications (NRC, 1994) for all essential ami no acids, except Thr. Feed intake, BW gain, and feed:gain responses we re measured, Average environmental temperatures for Weeks 1, 2, and 3 were 29 27, and 24 C, respectively. From 4 to 9 wk of age, average env ironmental temperatures varied between 24 and 35 C. Turkeys in each ti me period responded to Thr in a curvilinear manner with responses at t he asymptote being equivalent to turkeys fed the corn-soybean meal con trol diets. Adequate dietary Thr levels for gain and feed:gain for the 0 to 3 wk period were 0.93% (3.21 g Thr/Mcal ME) and 0.97% (3.34 g Th r/Mcal ME) of diet, respectively. From 3 to 6 wk of age, the level of dietary Thr needed to support adequate BW gain and feed:gain was 0.88% of diet (2.81 g Thr/Mcal ME). The level of dietary Thr needed to supp ort adequate BW gain and feed:gain from 6 to 9 wk of age was 0.77% of diet (2.30 g Thr/Mcal ME). These results indicate-that the NRC (1994) estimations of Thr needs up to 9 wk of age are more than adequate.