Eun J-S, Beauchemin K A
Agriculture and Agri-Food Canada, Research Centre, Lethbridge, Alberta, T1J 4B1, Canada.
J Dairy Sci. 2007 Jun;90(6):2839-51. doi: 10.3168/jds.2006-820.
A series of in vitro fermentation experiments was performed to assess the effects of 4 feed enzyme products (FE) that varied in enzymatic activities on the degradation of alfalfa hay and corn silage. The FE contained a range of endoglucanase, exoglucanase, xylanase, and protease activities, and a range of dose rates (DR) was used. The objective of the study was to identify effective formulations and optimum DR, and to establish if combining FE would further improve fiber degradation. For alfalfa hay, quadratic increases in gas production and degradation of dry matter (DM) and fiber were observed for all FE, with maximum responses at low to medium DR. For corn silage, none of the FE increased gas production or DM degradation, but all FE increased NDF degradation, with optimum DR in the low to medium range. The proteolytic enzyme papain improved fiber degradation of alfalfa hay and corn silage in a manner similar to that observed for polysaccharidase FE. Among the polysaccharidase FE, added activities of endoglucanase and exoglucanase were positively correlated with improvement in neutral detergent fiber (NDF) degradability of corn silage, whereas only added endoglucanase activity tended to be correlated with improvement in NDF degradability of alfalfa hay. Combining effective polysaccharidase FE further improved fiber degradation of both forages, with greater improvements for corn silage. Combining polysaccharidase and proteolytic FE further improved NDF degradation of corn silage, but not alfalfa hay. Combination treatments generally resulted in additive effects with increases in fiber degradation equal to the sum of the improvements for the individual enzyme components. Improved fiber degradation of corn silage was associated with decreased acetate to propionate ratios. Enzyme products that improve in vitro degradation of forages may have the potential to improve lactational performance of dairy cows.
进行了一系列体外发酵实验，以评估4种酶活性不同的饲料酶产品（FE）对苜蓿干草和玉米青贮饲料降解的影响。这些FE含有一系列的内切葡聚糖酶、外切葡聚糖酶、木聚糖酶和蛋白酶活性，并使用了一系列剂量率（DR）。本研究的目的是确定有效的配方和最佳DR，并确定联合使用FE是否会进一步改善纤维降解。对于苜蓿干草，所有FE均观察到产气量、干物质（DM）和纤维降解呈二次增加，在低至中等DR时反应最大。对于玉米青贮饲料，没有一种FE增加产气量或DM降解，但所有FE均增加了中性洗涤纤维（NDF）降解，最佳DR在低至中等范围内。蛋白水解酶木瓜蛋白酶改善苜蓿干草和玉米青贮饲料纤维降解的方式与多糖酶FE相似。在多糖酶FE中，内切葡聚糖酶和外切葡聚糖酶的添加活性与玉米青贮饲料中性洗涤纤维（NDF）降解率的提高呈正相关，而只有添加的内切葡聚糖酶活性倾向于与苜蓿干草NDF降解率的提高相关。联合使用有效的多糖酶FE进一步改善了两种牧草的纤维降解，对玉米青贮饲料的改善更大。联合使用多糖酶和蛋白水解FE进一步改善了玉米青贮饲料的NDF降解，但对苜蓿干草没有改善。联合处理通常产生累加效应，纤维降解的增加等于各个酶组分改善效果的总和。玉米青贮饲料纤维降解的改善与乙酸与丙酸比例的降低有关。改善牧草体外降解的酶产品可能有潜力提高奶牛的泌乳性能。
