Fan M Z, Sauer W C
Department of Animal and Poultry Science, University of Guelph, Ontario, Canada.
J Anim Sci. 2002 Jun;80(6):1593-605. doi: 10.2527/2002.8061593x.
This study was conducted to determine true ileal AA digestibility coefficients and the endogenous AA outputs associated with barley samples for growing-finishing pigs using the regression analysis technique with dual digestibility markers. Six barrows, with 30.5 and 58.6 kg average initial and final BW, were fitted with a simple T-cannula at the distal ileum and fed six barley-based diets at close to ad libitum feed intake according to a 6 x 6 Latin square design. The six diets contained 97% of six barley samples varying from low to high in CP and AA contents (8.5, 9.2, 9.8, 11.5, 12.6, and 15.6% CP, respectively, on DM basis). The dietary NDF content ranged from 16.8 to 23.8% on DM basis. Chromic oxide (Cr2O3) and acid-insoluble ash (AIA) were used as digestibility markers. Each experimental period lasted 7 d. Ileal digesta were collected, at 2-h intervals, for a total of 24 h during d 6 and 7. There were linear relationships (P < 0.01) between dietary contents of apparent ileally digestible and total CP and AA as determined by using either Cr2O3 or AIA as a digestibility marker. The use of Cr2O3 vs AIA affected (P < 0.01) the determination of true ileal AA digestibility coefficients and the endogenous CP and AA outputs. However, there were no differences (P > 0.01) in the true ileal AA digestibility coefficients in barley samples between this study and the average values reported in the literature. The endogenous CP and AA outputs determined in this study were higher (P < 0.01) than reported values (35.1+/-3.0 vs 14.7+/-1.1 g CP/kg DMI). It is concluded that dual digestibility markers should be used to measure true ileal AA digestibility coefficients and endogenous AA outputs when dietary fiber content is high and the ileal digesta is collected through a simple T-cannula in the pig. True rather than apparent ileal AA digestibility coefficients determined in barley samples should be used in diet formulation for swine. The gastrointestinal endogenous AA secretion, recycling, and output losses are important in whole-body AA utilization and homeostasis, especially when fiber-enriched diets are fed to growing-finishing pigs.
本研究旨在使用双消化率标记物的回归分析技术，测定生长育肥猪大麦样品的真回肠氨基酸消化率系数以及与之相关的内源性氨基酸排出量。选用6头平均初始体重30.5 kg、终末体重58.6 kg的公猪，在回肠末端安装简单的T形套管，并根据6×6拉丁方设计，以接近自由采食的量饲喂6种以大麦为基础的日粮。这6种日粮包含6种大麦样品的97%，其粗蛋白和氨基酸含量从低到高不等（以干物质计，粗蛋白含量分别为8.5%、9.2%、9.8%、11.5%、12.6%和15.6%）。日粮中性洗涤纤维含量以干物质计在16.8%至23.8%之间。氧化铬（Cr2O3）和酸不溶性灰分（AIA）用作消化率标记物。每个试验期持续7天。在第6天和第7天，每隔2小时收集一次回肠食糜，共收集24小时。使用Cr2O3或AIA作为消化率标记物时，日粮中表观回肠可消化粗蛋白和总粗蛋白及氨基酸含量之间存在线性关系（P<0.01）。使用Cr2O3和AIA对真回肠氨基酸消化率系数以及内源性粗蛋白和氨基酸排出量的测定有影响（P<0.01）。然而，本研究中大麦样品的真回肠氨基酸消化率系数与文献报道的平均值之间没有差异（P>0.01）。本研究测定的内源性粗蛋白和氨基酸排出量高于报道值（35.1±3.0对14.7±1.1 g粗蛋白/kg干物质采食量）。得出结论，当膳食纤维含量高且通过猪的简单T形套管收集回肠食糜时，应使用双消化率标记物来测定真回肠氨基酸消化率系数和内源性氨基酸排出量。在猪日粮配方中应使用大麦样品中测定的真回肠氨基酸消化率系数而非表观消化率系数。胃肠道内源性氨基酸的分泌循环和排出损失在全身氨基酸利用和内稳态中很重要，尤其是当给生长育肥猪饲喂富含纤维的日粮时。
