仿生消化系统测定玉米和大豆粕酶水解物能值影响因素的研究

本试验旨在通过探讨饲料样品的粉碎粒度、未水解残渣的清洗次数和透析袋处理后的存放时间对仿生消化法中玉米、大豆粕干物质消化率和酶水解物能值的影响，为确立基于仿生消化系统（ＳＤＳ １）测定饲料酶水解物能值的操作规程提供参考。试验采用单因素完全随机设计，共设１１个处理，每个处理５个重复，每个重复１根消化管。其中处理１～３、４～７、８～１１分别考察饲料样品的粉碎粒度、未消化残渣的清洗次数、透析袋处理后的存放时间对玉米和大豆粕干物质消化率及酶水解物能值的影响。结果表明：１）粉碎粒度对玉米、大豆粕的干物质消化率和酶水解物能值都有显著性影响（Ｐ＜０．０５）。当玉米的粉碎粒度从 ４０目减少到 １００目时，其干物质消化率和酶水解物能值依次增加，而且变化幅度较大的粒度范围出现在 ４０～６０目。而大豆粕的粉碎粒度从４０目减少到１００目时，尽管６０目样品的干物质消化率与酶水解物能值最高，但与其他 ２个粉碎粒度样品的干物质消化率相差在 ０．７０％以内。２）未消化残渣的清洗次数对玉米、大豆粕的干物质消化率与酶水解物能值均有显著性影响（Ｐ＜０．０５）。随着清洗次数的增加，玉米、大豆粕的干物质消化率和酶水解物能值逐步趋于稳定。在清洗 ６次后，玉米、大豆粕的干物质消化率与酶水解物能值的变异已趋于 ＳＤＳ １的测定误差的允许范围之内。３）透析袋处理后的存放时间对玉米、大豆粕的干物质消化率和酶水解物能值也有显著性影响（Ｐ＜０．０５），但在 ４个存放时间的处理水平内，玉米、大豆粕的干物质消化率、酶水解物能值的变化都在０．９４％和 ０．３７ＭＪ／ｋｇ以内，处于 ＳＤＳ １测定误差的允许范围内。综合上述结果，ＳＤＳ １测定饲料酶水解物能值时，样品的粉碎粒度应为 ６０目、未消化残渣的清洗次数为 ６次。透析袋前处理后 ４℃下存放 ９０ｄ内均可用于对玉米、大豆粕干物质消化率和酶水解物能值的测定。

Factors Affecting the Measurement of Enzymatic Hydrolysate Gross Energy of Corn and Soybean Meal Using Simulative Digestion System

This experiment was conducted to study on sample particle size,wash times of undigested residues,and preservation time of treated dialysis bag affecting the determination of dry matter digestibility(DMD) and enzymatic hydrolysate gross energy(EHGE) of corn and soybean meal using an in vitro digestion method based on simulative digestion system.It would provide a reference to develop a method for measuring the EHGE of feed using simulative digestion system.A single factor completely randomized design with 11 treatments was adapted.Each treatment contained 5 replicates with 1 digestion tube per replicate.The treatments 1-3,4-7 and 8-11 were used to determine the effects of sample particle size,wash times of undigested residues,and preservation time on DMD and EHGE of corn and soybean meal,respectively.The results showed as follows: 1) sample particle size significantly affected the DMD and EHGE of corn and soybean meal(P<0.05).When particle size was decreased from 40 mesh to 100 mesh,the DMD and EHGE of corn were increased.The changes of DMD and EHGE of corn were both more obvious in particle size ranged from 40 mesh to 60 mesh.However,when particle size was decreased from 40 mesh to 100 mesh,the DMD and EHGE of soybean meal with 60 mesh were higher than those of the samples with 40 mesh and 100 mesh.And the difference of DMD of soybean meal with 40,60 and 100 mesh was not more than 0.70%.2) The wash times of undigested residues significantly affected the DMD and EHGE of corn and soybean meal(P<0.05).The DMD and EHGE of corn and soybean meal became stable when increasing wash times of undigested residues.After washing undigested residues for above 6 times,the variations of DMD and EHGE of corn and soybean meal both were in the permitted range of systematic error of simulative digestion system.3) The preservation time of treated dialysis bag also significantly affected the DMD and EHGE of corn and soybean meal(P<0.05).However,in the 4 treatments,the differences of the DMD and EHGE of corn and soybean meal were not more than 0.94% and 0.37 MJ/kg,respectively,which were in the permitted range of systematic error of simulative digestion system.In conclusion,60 mesh sample particle size and 6 times for washing undigested residues are the suitable condition in determination of EHGE of feed using the in vitro digestion method based on simulative digestion system.Preservation of treated dialysis bag for 90 d and at 4 ℃ don’t obviously affect the DMD and EHGE of corn and soybean meal.