饲用酶制剂在反刍动物营养中的应用进展

摘要

一般情况下,在瘤胃中粗饲料细胞壁组分的消化利用率较低,由于其复杂紧密的结构限制了动物对粗饲料的利用.因此,在反刍动物生产中提高粗饲料利用率的应用研究是非常必要的,不仅改善饲料利用率、提高动物生产性能,还为饲料资源的开发与利用乃至为畜牧业发展提供有效途径.而饲用酶制剂以其绿色、环保、安全等特点成为了该研究领域的热点.通常采用体外和半体内法评定酶制剂处理对粗饲料体外发酵和瘤胃降解特性的影响,并采用体内法评价酶制剂在反刍动物营养中的应用效果.研究表明,外源酶制剂的应用能够有效提高饲料消化率、奶牛产量、肉牛增重和肉羊增重,但其效果不一致,其效果受很多因素的影响,包括酶种类、酶活性、饲粮组成、添加水平.添加方式、动物种类及生长性能等.另外,由于人们对所用酶产品的生化特性掌握不足,导致了对其作用机理、优化条件及影响其作用效果因子的了解不够充分.如酶活性作为酶制剂最主要的生化特性,在使用前往往被忽略检测,并且目前国内外对酶活性的检测及质量评定还没有统一的标准.然而研究结果间直接进行比较也是不科学不合理的.本研究主要从饲用酶制剂的发展历程,反刍动物营养中纤维降解酶的作用机理、应用效果和影响其作用效果的因素以及存在问题等方面进行了综述,旨在为饲用酶制剂在反刍动物营养中的应用提供系统的科学知识.%Digestion of cell wall fractions of fiber in the rumen is incomplete due to its resistance to microbial degradation.The ability to effectively utilise forage with high fiber content is important for the development of efficient animal husbandry systems.Exogenous enzymes able to modify forages before feeding are of considerable interest to researchers;important potential benefits include improved environmental outcomes.In situ assessment and in vitro gas production were used to evaluate rumen degradation characteristics and in vitro fermentation characteristics of forage.An in vivo study was used to evaluate the effects of exogenous enzyme application to ruminant forage.Recent studies have shown that adding exogenous enzymes to ruminant diets can increase animal production as a result of enhanced digestion of feed,although results have been inconsistent.This inconsistency is due to range of factors including enzyme properties,diet composition,enzyme addition rates,animal species and animal growth performance.One of the main problems for researchers is the lack of adequate biochemical characterization of different enzymes which leads to a poor understanding of their mode of action and effectiveness.The biochemical characteristics of enzymes are very important but enzymes are not always evaluated prior to use and there are no global standards for assessing the activity and quality of enzymes.This paper reviews the research on the development of exogenous fibrolytic enzyme use in animal production,mechanisms of activity on plant cell walls,animal responses,the factors influencing the use of exogenous enzymes in ruminant nutrition and problems associated with their use.The aim of the review is to help the development of improved,safer and more consistent enzyme additives for use in ruminant nutrition.