Wheeler K B, Latshaw J D
Poult Sci. 1981 Jan;60(1):228-36. doi: 10.3382/ps.0600228.
Total sulfur amino acid (TSAA) requirements and methionine and cystine combinations were investigated during two growth phases (0 to 21 days and 21 to 42 days) of broilers using practical-type diets. For the first growth phase (0 to 21 days), the basal diet contained .62% TSAA to which increasing increments of DL-methionine were added. Both overall growth and feed efficiency improved as methionine levels increased to a level of .82% TSAA. When methionine-cystine combinations were used with the same basal diet, it was found that cystine could supply 54% of the TSAA content. When expressed on a millimolar basis, the methionine requirement was 41%, while cystine could account for 59% of the TSAA's. During the second growth phase (21 to 42 days) a basal diet consisting of .52% TSAA was used along with DL-methionine supplements to determine sulfur amino acid requirements. The trend was towards a slight decrease in requirement from .82% during the first growth period, to between .70% and .76% TSAA in the diet, represented mainly by methionine. When sulfur amino acid combinations were used during this period it appeared the replacement value of cystine for methionine decreased to between 38 and 43% of the TSAA level. Results also suggested that a more efficient way to express the sulfur amino acid requirement may be on a mole per unit of feed basis.
采用实用型日粮，对肉鸡两个生长阶段（0至21日龄和21至42日龄）的总含硫氨基酸（TSAA）需求以及蛋氨酸和胱氨酸组合进行了研究。在第一个生长阶段（0至21日龄），基础日粮含0.62%的TSAA，并添加递增剂量的DL-蛋氨酸。随着蛋氨酸水平增至0.82%TSAA，整体生长性能和饲料效率均得到改善。当在相同基础日粮中使用蛋氨酸-胱氨酸组合时，发现胱氨酸可提供TSAA含量的54%。以毫摩尔为基础表示时，蛋氨酸需求量为41%，而胱氨酸可占TSAA的59%。在第二个生长阶段（21至42日龄），使用含0.52%TSAA的基础日粮及DL-蛋氨酸补充剂来确定含硫氨基酸需求。需求趋势呈略微下降，从第一个生长阶段的0.82%降至日粮中TSAA的0.70%至0.76%，主要由蛋氨酸构成。在此期间使用含硫氨基酸组合时，胱氨酸替代蛋氨酸的价值似乎降至TSAA水平的38%至43%。结果还表明，以每单位饲料的摩尔数来表示含硫氨基酸需求可能是一种更有效的方法。
