Golian A, Guenter W, Hoehler D, Jahanian H, Nyachoti C M
Department of Animal Sciences, Ferdowsi University of Mashhad, Mashhad, Iran 1163-91775.
Poult Sci. 2008 Apr;87(4):706-12. doi: 10.3382/ps.2007-00330.
The purpose of this study was to compare estimates of ileal endogenous amino acid (IEAA) losses determined in broiler chicks with a nitrogen-free diet (NFD), diets containing highly digestible proteins as intact casein or enzymatically hydrolyzed casein (EHC), and the regression method (RM). Male Ross 308 broiler chicks were fed a commercial starter diet from d 1 to 15 of age and the following test diets from d 15 to 21: NFD and diets containing 5, 10, or 15% casein or EHC as the sole protein source. All diets contained chromic oxide as a digestibility marker. Each diet was assigned to 6 replicate cages, with 10 birds each. On d 21, birds were euthanized to sample ileal digesta. Feeding increasing levels of EHC or casein linearly (P<0.0001) increased IEAA flow. Nonlinearity (P<0.05) was detected for Ile, Val, Glu, and Ser with EHC and for Met with casein. Compared with the NFD method, IEAA values extrapolated to zero EHC or casein intake were similar for all amino acids except Ile (200 vs. 321 mg/kg of DM intake), Val (270 vs. 341 mg/ kg of DM intake), Ala (217 vs. 262 mg/kg of DM intake), and Ser (343 vs. 577 mg/kg of DM intake), whose flows were higher with EHC (P<0.05). The present results show that IEAA values determined with the NFD, EHC, and casein diets, at different inclusion levels, were different for most amino acids and that, for all amino acids, the values obtained with NFD and RM involving feeding graded levels of casein or EHC were comparable. Thus, using IEAA values obtained with either the NFD or the RM to calculate standardized ileal amino acid digestibility coefficients will give similar values.
本研究的目的是比较用无氮日粮（NFD）、含有高消化率蛋白质（如完整酪蛋白或酶解酪蛋白（EHC））的日粮以及回归法（RM）测定的肉鸡回肠内源氨基酸（IEAA）损失估计值。雄性罗斯308肉鸡从1日龄至15日龄饲喂商业育雏日粮，从15日龄至21日龄饲喂以下试验日粮：NFD以及含有5%、10%或15%酪蛋白或EHC作为唯一蛋白质来源的日粮。所有日粮均含有氧化铬作为消化率标记物。每种日粮分配到6个重复笼中，每个笼中有10只鸡。在21日龄时，对鸡实施安乐死以采集回肠食糜样本。线性增加EHC或酪蛋白的饲喂水平（P<0.0001）会使IEAA流量增加。对于EHC组的异亮氨酸、缬氨酸、谷氨酸和丝氨酸以及酪蛋白组的蛋氨酸，检测到非线性（P<0.05）。与NFD法相比，外推至EHC或酪蛋白摄入量为零时的IEAA值，除异亮氨酸（200对321mg/kg干物质摄入量）、缬氨酸（270对341mg/kg干物质摄入量）、丙氨酸（217对262mg/kg干物质摄入量）和丝氨酸（343对577mg/kg干物质摄入量）外，所有氨基酸的IEAA值相似，EHC组这些氨基酸的流量更高（P<0.05）。目前的结果表明，在不同添加水平下，用NFD、EHC和酪蛋白日粮测定的IEAA值，对于大多数氨基酸而言是不同的，并且对于所有氨基酸，用NFD和涉及饲喂分级水平酪蛋白或EHC的RM获得的值具有可比性。因此，使用用NFD或RM获得的IEAA值来计算标准化回肠氨基酸消化率系数将得到相似的值。
