Studies on the Improvement of the Nutritive Calue of Low Quality Roughage

秸秆等低品质粗饲料是反刍动物饲料中最丰富但营养价值较低的资源，近年来，通过物理、化学和生物处理提高其营养价值的研究较多。低品质粗饲料通常氮含量不足，纤维降解缓慢，限制了其自愿摄入。适当的氮补充可以增加动物的自愿摄入量，提高动物对氮的利用，有时还可以提高纤维的消化率。反刍动物营养期牧草的纤维消化率很高，但含有过量的可溶性营养物质。这些多余的可以很容易地去除成绿色果汁（GJ）压榨他们留下的营养残留物作为物质作物。GJ含有丰富的蛋白质和可溶性成分，可作为低氮饲料的良好添加源。如果在加入秸秆前进行碱化处理，纤维消化率也有望提高。稻秆青贮中添加GJ以使水分含量达到70%，其粗蛋白质含量比加水青贮的高3-4%。添加NaOH处理后的GJ不仅能有效提高纤维组分的消化率，还能通过降低瘤胃氨浓度、血浆尿素水平和尿氮排泄量来增加动物的氮潴留。但添加NaOH对稻草青贮纤维消化率的提高比添加氨处理的GJ低10%。两种碱处理青贮之间差异的原因仍在研究中，但可能是由于它们之间的氮含量不同。

Recently, many researches have been conducted on improving the nutritive value of low quality roughage such as straw, which is a most abundant but little nutritious resources as ruminant feed, by physical, chemical and biological treatments. Low quality roughage usually has insufficient level of nitrogen and slowly degradable fiber, which limits its voluntary intake. An adequate nitrogen supplement increases the voluntary intake, improves N utilization in animals and sometimes improves fiber digestibility.While herbages in vegetative stage are very high in fiber digestibility but contain excess soluble nutrients for ruminants. This excess can be easily removed into Green Juices (GJ) by pressing them leaving as nutritious residue as material crop.GJ contains much protein and soluble components and consequently may serve as a good additive source for low nitrogen feeds. If it is alkalized before addition to straw, an improvement of fiber digestibility can also be expected.Rice straw silage added with GJ at ensiling as to make the moisture content to 70%, contained 3-4% more crude protein than those ensiled with water. Addition of NaOH treated GJ was not only effective on improving the digestibility of fibrous components but also on increasing nitrogen retention of animals by reducing ruminal ammonia concentration, plasma urea level and urinary N excretion. But the improved fiber digestibility by the NaOH addition was 10% lower than that obtained on the rice straw silage added with ammonia treated GJ. The reason of the difference between the two alkali-treated silages are still under investigation but may be attributable to the different N content between them.