Webel D M, Fernandez S R, Parsons C M, Baker D H
Department of Animal Sciences, University of Illinois, Urbana 61801, USA.
Poult Sci. 1996 Oct;75(10):1253-7. doi: 10.3382/ps.0751253.
Four experiments were conducted to determine the digestible Thr requirement of commercial broiler chickens (Ross x Hubbard) during the period 3 to 6 and 6 to 8 wk posthatching. Threonine-deficient corn-peanut meal basal diets (3,200 MEn/kg) contained 20% CP and 0.50% Thr for 3- to 6-wk-old birds, and 18.3% CP and 0.50% Thr for 6- to 8-wk-old birds. True digestibility assessment using cecectomized roosters indicated that Thr was 81% digestible in both basal diets. Thus, both diets contained 0.40% digestible Thr. Growth rate and feed efficiency of chicks fed the corn-peanut meal basal diets supplemented with surfeit Thr was equal to that of chicks fed a 20% CP Met-fortified corn-soybean meal diet. Graded doses of Thr produced marked responses (P < 0.05) in weight gain and feed efficiency in birds of both age groups. Maximal feed efficiency was achieved at 0.61% digestible Thr in 3- to 6-wk-old birds and at 0.52% digestible Thr in 6- to 8-wk-old birds. Extrapolating these digestible Thr requirements to total requirements for chicks consuming corn-soybean meal diets (Thr digestibility = 87%) results in estimates of 0.70 and 0.60% for broiler chickens during the growth periods 3 to 6 and 6 to 8 wk posthatching, respectively. These estimates are lower than those of NRC (1994) but are in close agreement with those obtained from ideal protein calculations, i.e., Thr requirements should be 70% of lysine requirements for chicks 3 to 8 wk of age.
进行了四项试验，以确定商品肉鸡（罗斯×哈伯德）在出壳后3至6周龄以及6至8周龄期间可消化苏氨酸的需求量。缺乏苏氨酸的玉米-花生粕基础日粮（代谢能3200千卡/千克），3至6周龄的鸡日粮含20%粗蛋白和0.50%苏氨酸，6至8周龄的鸡日粮含18.3%粗蛋白和0.50%苏氨酸。采用盲肠切除公鸡进行的真消化率评估表明，两种基础日粮中苏氨酸的消化率均为81%。因此，两种日粮均含0.40%可消化苏氨酸。饲喂添加过量苏氨酸的玉米-花生粕基础日粮的雏鸡，其生长速度和饲料效率与饲喂含20%粗蛋白且蛋氨酸强化的玉米-豆粕日粮的雏鸡相当。两个年龄组的鸡，随着苏氨酸添加量的增加，体重增加和饲料效率均出现显著反应（P<0.05）。3至6周龄的鸡，可消化苏氨酸含量为0.61%时饲料效率最高；6至8周龄的鸡，可消化苏氨酸含量为0.52%时饲料效率最高。将这些可消化苏氨酸需求量推算为采食玉米-豆粕日粮雏鸡的总需求量（苏氨酸消化率=87%），结果表明，出壳后3至6周龄和6至8周龄的肉鸡，苏氨酸需求量分别为0.70%和0.60%。这些估计值低于NRC（1994）的估计值，但与根据理想蛋白质计算得出的结果非常接近，即3至8周龄雏鸡的苏氨酸需求量应为赖氨酸需求量的70%。
