Baker D H, Fernandez S R, Webel D M, Parsons C M
Department of Animal Sciences, University of Illinois, Urbana 61801, USA.
Poult Sci. 1996 Jun;75(6):737-42. doi: 10.3382/ps.0750737.
Three experiments were conducted with commercial broiler chicks to determine the SAA requirement during the growth period 3 to 6 wk posthatching. A 20% CP corn-peanut meal basal diet (3,200 kcal ME(n)/kg) was analyzed to contain 0.23% Met and 0.28% cystine. True digestibility assessment in cecectomized cockerels revealed that Met and cystine in the basal diet were 81 and 75% digestible, respectively. Therefore, the basal diet contained 0.19% digestible Met and 0.21% digestible cystine. When fully fortified with DL-Met, growth rate and feed efficiency of chicks fed the corn-peanut meal diet were equal to that of chicks fed a 20% CP Met-fortified corn-soybean meal diet. In the SAA requirement assay, Ross x Hubbard male chicks were fed graded increments of DL-Met (0.03%) and L-cystine (0.03%) to achieve digestible SAA concentrations of 0.40, 0.46, 0.52, 0.58, 0.64, and 0.70%. Weight gain and feed efficiency responded quadratically (P < 0.01) to increasing doses of SAA. The estimated requirement for maximal feed efficiency was higher than that for maximal weight gain. Both visual appraisal and curve fitting procedures suggested a requirement of close to 0.61% digestible SAA. When extrapolated to a corn-soybean meal diet where SAA true digestibility is 87.5%, the total SAA requirement calculates to be 0.70% of the diet. However, because commercial corn-soybean meal diets typically contain supplemental Met, which is only 81% efficient (wt:wt) in furnishing cystine, the estimated total SAA requirement for chicks fed 20% CP Met-fortified corn-soybean meal diets with 3,200 kcal of ME/kg would probably approximately 0.72% of the diet. A DL-Met vs L-cystine supplementation assay suggested that digestible cystine can supply no more than 52% of the total requirement for digestible SAA of chicks during the 3- to 6-wk growth period.
进行了三项试验，以确定商品肉仔鸡在出壳后3至6周生长阶段的总含硫氨基酸（SAA）需要量。分析一种20%粗蛋白的玉米-花生粕基础日粮（3200千卡代谢能/千克），其蛋氨酸含量为0.23%，胱氨酸含量为0.28%。对去盲肠公鸡进行的真消化率评估表明，基础日粮中蛋氨酸和胱氨酸的消化率分别为81%和75%。因此，基础日粮中可消化蛋氨酸含量为0.19%，可消化胱氨酸含量为0.21%。用DL-蛋氨酸完全强化后，饲喂玉米-花生粕日粮的雏鸡生长速度和饲料效率与饲喂20%粗蛋白蛋氨酸强化玉米-豆粕日粮的雏鸡相当。在总含硫氨基酸需要量测定中，给罗斯×哈伯德雄性雏鸡饲喂梯度增加的DL-蛋氨酸（0.03%）和L-胱氨酸（0.03%），以使可消化总含硫氨基酸浓度达到0.40%、0.46%、0.52%、0.58%、0.64%和0.70%。体重增加和饲料效率对总含硫氨基酸剂量增加呈二次反应（P<0.01）。最大饲料效率的估计需要量高于最大体重增加的需要量。视觉评估和曲线拟合程序均表明，可消化总含硫氨基酸的需要量接近0.61%。外推至总含硫氨基酸真消化率为87.5%的玉米-豆粕日粮时，总含硫氨基酸需要量计算为日粮的0.70%。然而，由于商品玉米-豆粕日粮通常含有补充蛋氨酸，其提供胱氨酸的效率仅为8l%（重量比），因此，对于饲喂含3200千卡代谢能/千克、20%粗蛋白蛋氨酸强化玉米-豆粕日粮的雏鸡，估计总含硫氨基酸需要量可能约为日粮的0.72%。一项DL-蛋氨酸与L-胱氨酸补充试验表明，在3至6周生长阶段，可消化胱氨酸对雏鸡可消化总含硫氨基酸总需要量的供应比例不超过52%。
