套算法与消化率计算法测定鸭饲粮脂肪代谢能值的比较研究

A Comparative Study on the Metabolizable Energy of Dietary Fats Determined by the Difference Method and Digestibility Calculation Method in Ducks

本研究旨在通过比较套算法与消化率计算法测定鸭饲粮脂肪代谢能值中内源性干扰、测试精度的差异，探讨测定脂肪代谢能值的适宜生物学方法。试验 １是比较套算法和消化率计算法测定饲粮脂肪真代谢能值的差异。饲粮脂肪设 ４个处理，饲粮 ４为不添加油脂的基础饲粮，饲粮 １、２、３分别为添加了玉米油、大豆油和猪油的试验饲粮。通过代谢试验测定饲粮 １～４脂肪的真代谢能值。试验 ２是在试验 １筛选出的消化率计算法的基础上，探讨在不同类型的饲粮背景条件下脂肪真代谢能值的差异。采用两因素完全随机设计，即饲粮设 ２个处理（玉米 －豆粕饲粮和玉米淀粉饲粮），脂肪设 ３个处理［玉米油 ＋大豆油 １（５．２２∶１）、玉米油 ＋大豆油 ２（１．９０∶１）、玉米油 ＋大豆油 ＋猪油（１４．２８∶３．５０∶４）］。通过代谢试验测定饲粮 ５～１０的能量及脂肪的摄入量、排泄量。结果表明，套算法中由内源性粪能排泄量引起的饲粮脂肪真代谢能值的变异系数为 １１．３９％，消化率计算法中由内源性脂肪排泄量引起的饲粮脂肪真代谢能值的变异系数为 １．４３％。套算法测定的 ３种脂肪的平均变异系数及重复内最大值、最小值和极差分别为２２．３９％、４１．７０ＭＪ／ｋｇ、２４．７７ＭＪ／ｋｇ、１６．９４ＭＪ／ｋｇ，而消化率计算法测定的分别为 ４．４４％、３６．２３ＭＪ／ｋｇ、３３．０３ＭＪ／ｋｇ、３．１９ＭＪ／ｋｇ。通过消化率计算法测定 ２种饲粮背景条件下：玉米油 ＋大豆油组成的混合油脂的真代谢能值无显著性差异（Ｐ＞０．０５），但玉米油 ＋大豆油 ＋猪油组成的混合油脂的真代谢能值存在显著性差异（Ｐ＜０．０５）。综上，消化率计算法测定鸭饲粮脂肪代谢能值比套算法受内源性干扰更少，重复性更高，但饲粮的组成成分对脂肪的真代谢能值仍有一定影响。

This experiment was conducted to study the proper biological method for determining the metabolizable energy of dietary fats in ducks according to the influence of endogenous excreta and the test precision using difference method and digestibility calculation method.Experiment 1 was to study the difference of true metabolizable energy of dietary fats determined by difference method and digestibility calculation method in ducks.The true metabolizable energy of fats in 4 diets with no fat（basal diet,diet 4）,corn oil（diet 1）,soybean oil（diet 2） and lard（diet 3）,respectively,were determined in this experiment.Experiment 2 was conducted to determine the difference of true metabolizable energy of fats mixed with two diets by digestibility calculation method which was selected according to the experiment 1.A two factorial randomized design with 2 treatments of diets（corn-soybean meal diet and corn starch diet） and 3 treatments of dietary fats（corn oil∶ soybean oil=5.22∶ 1,corn oil∶ soybean oil=1.90∶ 1,corn oil∶ soybean oil∶ lard=14.28∶ 3.40∶ 4） was adopted in this experiment.The true metabolizable energy of fats in diet 5~10 was determined.The results showed as follows： the coefficient of variation was 11.39% for true metabolizable energy of dietary fats from endogenous fecal energy using difference method,and that was 1.43% from endogenous fat using digestibility calculation method.The average coefficient of variation,and maximum,minimum and range in all replicates of the true metabolizable energy of the 3 fats were 22.39%,41.70 MJ/kg,24.77 MJ/kg,16.94 MJ/kg by difference method,and 4.44%,36.23 MJ/kg,33.03 MJ/kg,3.19 MJ/kg by digestibility calculation method,respectively.In digestibility calculation method,there was no significant difference in the true metabolizable energy of mixed fat combined by corn oil and soybean oil under two dietary treatments（P0.05）,but there was significant difference in that of mixed fat combined by corn oil,soybean oil and lard（P0.05）.It is shown that digestibility calculation method has less interference from endogenous loss and higher repeatability than difference method for the determination of metabolizable energy of dietary fats in ducks,but the metabolizable energy of dietary fats determined by digestibility calculation method is also affected by other dietary nutrients.