Wang X, Parsons C M
Department of Animal Sciences, University of Illinois, Urbana 61801, USA.
Poult Sci. 1998 Jul;77(7):1003-9. doi: 10.1093/ps/77.7.1003.
Experiments were conducted to determine whether the digestible Lys, Met, and TSAA in a high and low quality meat and bone meal (MBM) were totally bioavailable for protein synthesis in chicks. True digestibility of amino acids (AA) in the two MBM was determined by the precision-fed cecectomized rooster assay. Bioavailability of the digestible AA was then assessed in three slope-ratio chick growth assays using Lys-, Met-, or TSAA-deficient crystalline AA basal diets that were supplemented with varying levels of the test AA, high or low quality MBM, or AA mixtures simulating the mean digestible AA composition of the high and low quality MBM. Response parameters were weight gain, feed efficiency, body N gain, and body Lys gain in the Lys assay and weight gain and feed efficiency in the Met and TSAA assays. Bioavailability values for the digestible Lys, Met, and TSAA in the MBM and AA mixtures simulating MBM varied depending on response parameter, with values based on feed efficiency generally being highest. No consistent differences in bioavailability of the digestible AA were observed between the two MBM when all AA were considered; however, the bioavailability of the digestible Lys in the low quality MBM was lower than that in the high quality MBM for two of four performance criteria. When considering all response parameters and the AA mixture results, bioavailability of the digestible Lys and Met in the two MBM was generally 90% or greater, whereas bioavailability of the digestible TSAA was only 80% or less. The results of this study indicated that essentially all of the digestible Lys and Met in MBM were bioavailable for protein synthesis and metabolism but suggested that a significant amount of the TSAA, particularly Cys, was not bioavailable.
进行了多项实验，以确定优质和劣质肉骨粉（MBM）中的可消化赖氨酸、蛋氨酸和总含硫氨基酸（TSAA）是否能完全用于雏鸡的蛋白质合成。通过精确饲喂切除盲肠的公鸡试验测定了两种肉骨粉中氨基酸（AA）的真消化率。然后，在三项斜率比雏鸡生长试验中评估了可消化氨基酸的生物利用率，试验使用了缺乏赖氨酸、蛋氨酸或总含硫氨基酸的结晶氨基酸基础日粮，并添加了不同水平的待测氨基酸、优质或劣质肉骨粉，或模拟优质和劣质肉骨粉平均可消化氨基酸组成的氨基酸混合物。在赖氨酸试验中的反应参数为体重增加、饲料效率、体氮增加和体赖氨酸增加，在蛋氨酸和总含硫氨基酸试验中的反应参数为体重增加和饲料效率。肉骨粉和模拟肉骨粉的氨基酸混合物中可消化赖氨酸、蛋氨酸和总含硫氨基酸的生物利用率值因反应参数而异，基于饲料效率的值通常最高。当考虑所有氨基酸时，未观察到两种肉骨粉之间可消化氨基酸的生物利用率存在一致差异；然而，对于四项性能标准中的两项，劣质肉骨粉中可消化赖氨酸的生物利用率低于优质肉骨粉。当考虑所有反应参数和氨基酸混合物结果时，两种肉骨粉中可消化赖氨酸和蛋氨酸的生物利用率一般为90%或更高，而可消化总含硫氨基酸的生物利用率仅为80%或更低。本研究结果表明，肉骨粉中基本上所有可消化赖氨酸和蛋氨酸都可用于蛋白质合成和代谢，但表明大量的总含硫氨基酸，特别是半胱氨酸，无法被利用。
