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

本研究旨在建立一种适合于满足反刍动物的饲粮蛋白质评价方法，并比较几种热带牧草饲粮蛋白质在各种洗涤液中的溶解度分级方法。其次，研究了青贮发酵过程中加热和青贮后二次发酵对热带牧草青贮蛋白质含量和瘤胃降解的影响。结果如下：1)应用本研究方法，将饲粮蛋白质体系划分为瘤胃可降解蛋白质（氮× 6.25）分割为快溶和慢降解部分，瘤胃不可降解蛋白质分割为可消化和不消化部分。2)采用原位法和体外法测定反刍动物体内一种酸性洗涤不溶性氮（ADIN）。这两种新方法与ADIN显著相关（r=0.7 ~ 0.9），是ADF分析后可靠的氮替代方法。3)青贮提高了6种热带牧草的可降解蛋白含量，其中豆科牧草的趋势最为明显。4)青贮期间和青贮后高温和潮湿处理均降低了青贮干物质消化率和降解蛋白质含量，而不消化氮含量显著增加。

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.