PRODUCTION,CUMULATIVE PATTERN AND UTILIZATION OF PROTEIN FRACTIONATED IN TROPICAL FORAGE SPECIES.

本研究首先建立了一种适合反刍动物的蛋白质评价方法，并比较了几种热带牧草的蛋白质分级方法。其次，研究了青贮发酵过程中加热和青贮后二次发酵对几种热带牧草蛋白质组分和瘤胃降解的影响。结果表明：1）在本研究中，将瘤胃可降解蛋白质（氮× 6.25）分为快溶和慢降解组分，将瘤胃不可降解蛋白质分为可消化和不可消化组分，从而区分了日粮蛋白质体系。2)本文介绍了反刍动物体内酸性洗涤剂不溶性氮（ADIN）的原位和体外测定方法。这两种新方法与ADIN显著相关（r=0.7-0.9），是ADF分析后氮的可靠替代方法。3)6种热带牧草的可降解蛋白质组分均随青贮时间的延长而增加，以豆科牧草的趋势最为显著。4)青贮过程中和青贮后高温、高湿处理降低了青贮饲料的干物质消化率和蛋白质降解率，显著提高了青贮饲料中难消化氮的含量。

This study was firstly conducted to establish a suitable methods to evaluate dietary protein in terms of meeting ruminants, and compare a dietary protein fractionated based on solubility in each detergent solution between some tropical forages. Secondly, the effects of heating during silage fermentation and secondary fermentation after ensiling on protein fractions and degradation in rumen of some tropical forage silages were estimated. Results were as follows.1) When applying the methods in this study, dietary protein system s were distinguished a partition rumen degradable protein (nitrogen x 6.25) into quickly soluble and slowly degradated fractions and partition rumen undegradable protein into digestible and indigestible fractions. 2) The in situ and in vitro methods were introduced to measure an indigestible nitrogen in ruminants, which is characterized as acid detergent insoluble nitrogen (ADIN). These two new methods were significantly correlated with ADIN (r=0.7-0.9) and a reliable alternative to nitrogen after ADF analysis. 3) The degradable protein fraction in all the six tropical forage species were increased by ensiling, which tendency was remarkable in legumes. 4)The dry matter digestibility, degradated protein fraction were decreased, when silages were exposed to heat and moisture during and after ensiling, while indigestible nitrogen content were remarkably increased.