直接法与替代法测定羊草对肉用绵羊代谢能的比较研究

A Comparison on Metabolizable Energy of Leymus chinensis in Mutton Sheep Determined by Direct and Substitution Methods

本试验旨在比较直接法和替代法测定羊草对肉用绵羊代谢能。选用体重约为45.00kg的体况良好的杂交肉用羯羊30只,采用随机区组设计,分为5个处理,每个处理6个重复,每个重复1只羊,分别饲喂采用直接法的全羊草饲粮、用于替代法的基础饲粮(精粗比为1∶1)和3个试验饲粮,3个试验饲粮分别以60%、40%、20%羊草替代基础饲粮。饲粮均于08:00、18:00各饲喂600 g。试验每期19 d,包括预试期10 d,正试期9 d。结果表明:干物质、有机物、总能、粗蛋白质表观消化率为基础饲粮组>20%组>40%组>60%组>全羊草饲粮组,组间差异显著(P<0.05)。消化能与代谢能为基础饲粮组>20%组>40%组>60%组>全羊草饲粮组,组间差异显著(P<0.05)。代谢能与消化能比各组饲粮差异不显著(P>0.05)。直接法和替代法对测定原料羊草的粗蛋白质、中性洗涤纤维表观消化率影响不显著(P>0.05)。直接法中全羊草饲粮组的羊草干物质、有机物、总能表观消化率显著高于60%组(P<0.05),而与40%组、20%组之间差异不显著(P>0.05)。全羊草饲粮组羊草的消化能和代谢能显著高于60%组(P<0.05),与40%组、20%组之间差异不显著(P>0.05)。综合得出,直接法与替代法在测定羊草的代谢能时,替代比例不同会对结果产生显著影响,在采用替代法测定羊草的代谢能时,最佳的替代比例为20%。

This study aimed to compare metabolizable energy （ME） of Leymus chinensiS in mutton sheep de- termined by direct and substitution methods. Thirty crossbreed rams weighted about 45.0 kg were used and di- vided into 5 treatments with 6 replicates per treatment and 1 sheep per replicate according to a randomized block design. The diets in different treatments were as follows： full Leymus chinensis diet for direct method, and a basal diet （ forage ： concentrate ratio was 1：1 ） and three experimental diets （ the basal diet was replaced by Ley- mus chinensis at 60%, 40% and 20%） for substitution method. Diets were fed twice at 08：00 and 18：00 （ 600 g at each time point）. Each experiment period lasted for 19 d including 10 d of pretest period and 9 d of test period. The results showed as follows： the apparent digestibility of dry matter, organic matter, gross ener- gy and crude protein of showed that basal diet group〉20% group〉40% group〉60% group〉full Leymus chinen- sis diet group, and significant differences were found among groups （P〈0.05）. The digestible energy （DE） and ME showed that basal diet group〉20% group〉40% group〉60% group〉 full Leymus chinensis diet group, and significant differences were found among groups （P〈 0.05）. DM ： ME had no significant difference a- mong treatments （P 〉 0.05 ）. The apparent digestibility of crude protein and neutral detergent fiber had no difference between direct and substitutions methods. The apparent digestibility of dry matter, organic matter, and gross energy of Leymus chinensis in full Leymus chinensis diet group measured with direct method was sig- nificantly higher than those in 40% group （P〈0.05）, but had no significant difference with 20% group and 40% group （P〉0.05）. The DE and ME in full Leymus chinensis diet group were significantly higher than those in 60% group （P〈0.05）, and had no significant difference with 40% group and 20% group （P〉0.05）. In de- termination of ME of Leymus chinensis using direct and substitution methods, a significant difference is ob- served when the substitution proportion is different. The optimal substitution proportion is 20% when using sub- stitution method to measure ME.