奶牛常用粗饲料的瘤胃降解规律

本试验旨在研究 ２种苜蓿［黑龙江公农 １号苜蓿、美国安德森（Ａｎｄｅｒｓｏｎ）一级苜蓿］、黑龙江 ２种含杂量不同羊草（杂草率分别为 １０％、３４％）、全株玉米青贮、玉米秸秆青贮和玉米秸秆共 ７种粗饲料的瘤胃降解特性。试验选用 ８头装有永久性瘤胃瘘管的荷斯坦奶牛，采用尼龙袋法评定其干物质（ＤＭ）、粗蛋白质（ＣＰ）和中性洗涤纤维（ＮＤＦ）的瘤胃降解率和有效降解率。结果表明，美国安德森一级苜蓿、全株玉米青贮和黑龙江公农 １号苜蓿三者 ７２ｈＤＭ 降解率差异不显著（Ｐ＞０．０５），并显著高于其他 ４种粗饲料（Ｐ＜０．０５），而 ＤＭ有效降解率以美国安德森一级苜蓿最高，并与依次降低的黑龙江公农 １号苜蓿、全株玉米青贮和玉米秸秆青贮差异显著（Ｐ＜０．０５），羊草与玉米秸秆的 ＤＭ有效降解率显著低于其他粗饲料（Ｐ＜０．０５）。７２ｈＣＰ降解率及有效降解率以美国安德森一级苜蓿最高，且降解率与依次降低的黑龙江公农 １号苜蓿、全株玉米青贮、玉米秸秆青贮、杂草率为 １０％的羊草、玉米秸秆和杂草率为 ３４％的羊草间差异显著（Ｐ＜０．０５）。全株玉米青贮、玉米秸秆青贮 ７２ｈＮＤＦ降解率显著高于其他粗饲料（Ｐ＜０．０５）；而有效降解率以 ２种苜蓿较高，其次为玉米秸秆青贮与全株玉米青贮；降解率和有效降解率最低的均为杂草率为 ３４％的羊草。因此，从 ７种粗饲料在奶牛瘤胃的消化特性来看：１）美国安德森一级苜蓿营养价值最高，杂草率为 ３４％的羊草与玉米秸秆营养价值较低；２）羊草的品质受杂草率的影响；３）青贮能改善玉米秸秆的品质。

Rumen Degradation Characteristics of Commonly Used Roughages for Dairy Cows

This trial was conducted to study the rumen degradation characteristics of seven types of roughages: two kinds of alfalfa(American Anderson level 1 alfalfa and Heilongjiang Gongnong No.1 alfalfa),two kinds of Leymus chinensis with different contents of weeds(10% or 34%),corn silage,corn stover silage and corn stover.Nylon-bag technique was used to evaluate the rumen degradation rates and effective degradabilities of dry matter(DM),crude protein(CP),and neutral detergent fiber(NDF) of these roughages.The results showed as follows: DM degradation rates of American Anderson level 1 alfalfa,corn silage and Heilongjiang Gongnong No.1 alfalfa at 72 h were not significantly different(P>0.05),and were significantly higher than those of the other roughages.DM effective degradability of American Anderson level 1 alfalfa was significantly higher than that of Heilongjiang Gongnong No.1 alfalfa,corn silage and corn stover silage(P<0.05);Leymus chinensis and corn stover had the lower DM effective degradability than others(P<0.05).CP degradation rate and effective degradability of American Anderson level 1 alfalfa were the highest at 72 h among seven types of roughages,and the degradation rate was significantly higher than that of Heilongjiang Gongnong No.1 alfalfa,corn silage,corn stover silage,Leymus chinensis with 10% weeds,corn stover and Leymus chinensis with 34% weeds(P<0.05).NDF degradation rates of corn silage and corn stover silage at 72 h were significantly higher than those of the other roughages(P<0.05),but NDF effective degradabilities of two kinds of alfalfa were higher and followed by corn stover silage and corn silage;both NDF degradation rate and effective degradability of Leymus chinensis with 34% weeds were the lowest.In conclusion,for the degradation characteristics of seven types of roughages: 1) American Anderson level 1 alfalfa has the highest nutritional value,while Leymus chinensis with 34% weeds and corn stover have the lowest;2) the content of weeds affects the nutritional value of Leymus chinensis;3) the process of making silage can improve the nutritional value of corn stover.