Fernandez S R, Parsons C M
Department of Animal Sciences, University of Illinois, Urbana 61801, USA.
Poult Sci. 1996 Feb;75(2):216-23. doi: 10.3382/ps.0750216.
Previous research showed that formulation of chick diets containing cottonseed meal (CSM) using true digestible amino acid (AA) values was superior to formulation based on total AA; however, optimum growth performance could not be obtained from high CSM diets even when formulated on a digestible AA basis. Therefore, two experiments were conducted to determine whether the digestible AA in CSM were totally bioavailable or utilizable for protein synthesis. Soybean meal (SBM) was also evaluated for comparison. True digestibility of Lys and Val in CSM and SBM were determined using the precision-fed cecectomized rooster assay. Bioavailability was then assessed by chick growth assay using purified crystalline AA diets deficient in Lys or Val that were supplemented with varying levels of the test AA, CSM,SBM, or AA mixtures simulating the digestible AA composition of CSM and SBM. Multiple regression slope-ratio methodology indicated that bioavailability of the digestible Lys in CSM and the digestible Lys and Val in SBM did not differ (P > 0.05) from 100% for most response parameters. Bioavailability of the digestible Val in CSM ranged from 78 to 96% depending on response parameter. Bioavailabilities of crystalline Lys and Val in the AA mixtures simulating CSM and SBM were generally lower than the bioavailabililties of the digestible Lys and Val in CSM and SBM. The results of this study indicated that the digestible Lys and Val in SBM and CSM as measured by the precision-fed cecectomized rooster assay are totally or almost totally bioavailable for protein synthesis.
先前的研究表明，使用真可消化氨基酸（AA）值来配制含有棉籽粕（CSM）的雏鸡日粮，优于基于总氨基酸的配制方法；然而，即使以可消化氨基酸为基础配制，高棉籽粕日粮也无法获得最佳生长性能。因此，进行了两项试验，以确定棉籽粕中的可消化氨基酸是否完全可生物利用或可用于蛋白质合成。还对豆粕（SBM）进行了评估以作比较。使用精确饲喂的去盲肠公鸡试验测定了棉籽粕和豆粕中赖氨酸和缬氨酸的真消化率。然后通过雏鸡生长试验评估生物利用率，该试验使用缺乏赖氨酸或缬氨酸的纯化结晶氨基酸日粮，并补充不同水平的受试氨基酸、棉籽粕、豆粕或模拟棉籽粕和豆粕可消化氨基酸组成的氨基酸混合物。多元回归斜率比方法表明，对于大多数反应参数，棉籽粕中可消化赖氨酸以及豆粕中可消化赖氨酸和缬氨酸的生物利用率与100%没有差异（P>0.05）。棉籽粕中可消化缬氨酸的生物利用率根据反应参数在78%至96%之间。模拟棉籽粕和豆粕的氨基酸混合物中结晶赖氨酸和缬氨酸的生物利用率通常低于棉籽粕和豆粕中可消化赖氨酸和缬氨酸的生物利用率。本研究结果表明，通过精确饲喂的去盲肠公鸡试验测定的豆粕和棉籽粕中可消化赖氨酸和缬氨酸可完全或几乎完全用于蛋白质合成的生物利用。
