6种肉牛常用粗饲料瘤胃降解特性和瘤胃非降解蛋白质的小肠消化率

摘要

本试验旨在研究黑麦草、牛鞭草、甘薯蔓、玉米秸青贮、玉米秸秆和稻草共6种肉牛常用粗饲料的瘤胃降解特性和瘤胃非降解蛋白质（ RUP）的小肠消化率。选用3头装有永久性瘤胃瘘管的宣汉阉公牛为试验动物，采用尼龙袋技术评定6种粗饲料的干物质（ DM）、粗蛋白质（ CP）、中性洗涤纤维（ NDF）和酸性洗涤纤维（ ADF）瘤胃降解率，并用改进三步法评价RUP的小肠消化率。结果表明：1）黑麦草和甘薯蔓DM有效降解率较高，并与依次降低的牛鞭草、玉米秸青贮、玉米秸秆和稻草差异显著（ P＜0．05）。CP有效降解率和 ADF有效降解率以黑麦草最高，且与依次降低的甘薯蔓、牛鞭草、玉米秸青贮、玉米秸秆和稻草差异显著（ P＜0．05）。NDF有效降解率为黑麦草＞甘薯蔓＞玉米秸青贮＞牛鞭草＞稻草＞玉米秸秆，各粗饲料间差异显著（P＜0．05）。2）牛鞭草、玉米秸秆和稻草RUP的小肠消化率差异不显著（ P＞0．05），并显著高于依次降低的玉米秸青贮、黑麦草和甘薯蔓（ P＜0．05）。小肠可消化粗蛋白质含量为黑麦草＞甘薯蔓＞牛鞭草＞玉米秸青贮＞玉米秸秆＞稻草，各粗饲料间差异显著（ P＜0．05）。由此可见，不同粗饲料瘤胃降解特性不同，为小肠提供可消化粗蛋白质的潜力也不同。黑麦草的 DM、CP、NDF 和ADF在瘤胃的有效降解率最高，牛鞭草、玉米秸秆和稻草RUP的小肠消化率较高，黑麦草和甘薯蔓小肠可消化粗蛋白质含量较高。%This experiment was conducted to determine the ruminal degradation characteristics and small intesti-nal digestibility of rumen undegraded protein( RUP)of 6 kinds of commonly used roughages:ryegrass,hem-arthria compressa,sweet potato stem,corn stover silage,corn stover and rice straw. Three Xuanhan steers fit-ted with permanent ruminal cannulas were used. Nylon-bag technique was used to evaluate the ruminal degrad-ability and effective digestibility of dry matter( DM),crude protein( CP),neutral detergent fiber( NDF)and acid detergent fibre( ADF). Modified three-step in vitro method was used to evaluate small intestinal digestibil-ity of RUP of the roughages. The results showed as follows:1)the DM effective degradability of ryegrass and sweet potato stem was significantly higher than that of hemarthria compressa,corn stover silage,corn stover and rice straw( P<0.05),which were decreased in the above order. CP effective degradability and ADF effec-tive degradability of ryegrass were significantly higher than those of sweet potato stem,hemarthria compressa, corn stover silage,corn stover and rice straw( P<0.05),which were decreased in the above order. NDF effec-tive degradability showed ryegrass > sweet potato stem > corn straw silage > hemarthria compressa > corn sto-ver > rice straw,and the differences among roughages were significant( P<0.05). 2)The small intestinal di-gestibility of RUP of hemarthria compressa,corn stover and rice straw was not significantly different( P>0.05),and was significantly higher than that of corn stover silage,ryegrass and sweet potato stem( P<0.05), which was decreased in the above order. Intestinal digestible CP content of showed ryegrass > sweet potato stem >hemarthria compressa >corn stover silage >corn stover >rice straw ,and the differences among rough-ages were significant(P<0.05). In conclusion,ruminal degradation characteristics of roughages are dissimi-lar,and the potential that can provide digestible crude protein for small intestine is different. The effective de-gradability of DM,CP,NDF and ADF of ryegrass is the highest,small intestinal digestibility of RUP of hem-arthria compressa,corn stover and rice straw is higher,and ryegrass and sweet potato stem have higher intesti-nal digestible crude protein content.