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 (P>0.05), but there was significant difference in that of mixed fat combined by corn oil, soybean oil and lard (P<0.05). 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. ［Chinese Journal of Animal Nutrition, 2011, 23（7）：1176 -1184］
YIN Yugang,ZHAO Feng,LI Hui,ZHANG Hongfu,ZHANG Shiyuan
. A Comparative Study on the Metabolizable Energy of Dietary Fats Determined by the Difference Method and Digestibility Calculation Method in Ducks[J]. Chinese Journal of Animal Nutrition, 2011
, 23(07)
: 1176
-1184
.
DOI: 10.3969/j.issn.1006-267x.2011.07.016
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