粗饲料组合对奶牛饲粮养分消化率、能量和氮的利用的影响

本试验旨在研究粗饲料组合对奶牛饲粮养分消化率、能量和氮的利用的影响。试验采用单因素随机区组设计，将 １６头体重、年龄、胎次相近的，处于干奶期的健康荷斯坦奶牛分为 ４组，每组 ４头。以常用的粗饲料设计 Ａ（玉米青贮 ＋玉米秸秆）、Ｂ（玉米青贮 ＋羊草）、Ｃ（玉米青贮 ＋玉米秸秆 ＋羊草）、Ｄ（玉米青贮 ＋苜蓿草 ＋羊草）４种粗饲料组合的饲粮。结果表明：饲粮Ｄ干物质、有机物和中性洗涤纤维的消化率最高，显著高于其他各饲粮（Ｐ＜０．０５），其次为饲粮Ｂ和饲粮 Ｃ，饲粮 Ａ最低，显著低于其他各饲粮（Ｐ＜０．０５），各饲粮的酸性洗涤纤维消化率差异不显著（Ｐ＞０．０５）。粗饲料组合显著影响饲粮摄入总能、能量消化率和能量代谢率（Ｐ＜０．０５），饲粮 Ｄ甲烷能占摄入总能比显著低于其他 ３种饲粮（Ｐ＜０．０５）。各饲粮的粪氮、尿氮占摄入总氮比差异不显著（Ｐ＞０．０５），饲粮 Ｄ的氮消化率显著高于饲粮 Ｂ与饲粮 Ｃ（Ｐ＜０．０５），且饲粮 Ｂ显著高于饲粮 Ａ（Ｐ＜０．０５）；饲粮 Ｂ、饲粮 Ｄ的氮利用率显著高于饲粮 Ａ（Ｐ＜０．０５）。由此可见，玉米青贮 ＋苜蓿草 ＋羊草型饲粮的养分消化率、能量和氮的利用均优于其他各饲粮，羊草与玉米秸秆之间存在正组合效应，两者搭配使用可提高玉米秸秆的消化率，优化能量和氮的利用。

Effects of Forage Combinations on Nutrient Digestibility,Utilization of Energy and Nitrogen of Diets for Dairy Cows

This experiment was conducted to study the effects of forage combinations on nutrient digestibility,utilization of energy and nitrogen of diets for dairy cows.A single factor random block was used in this study.Sixteen Holstein cows were divided into four groups with four heads in each group.Four diets diet A(corn silage+corn stover),B(corn silage+Chinese wildrye),C(corn silage+corn stover+Chinese wildrye) and D(corn silage+alfalfa hay+Chinese wildrye)] of different combinations were designed with common forages.The results showed as follows: the digestibility of dry matter,organic matter and neutral detergent fibers of diet D was the highest,and was significantly higher than that of the other diets(P<0.05),followed by diet B and diet C;that of diet A was the lowest,and was significantly lower than that of the other diets(P<0.05);no significant difference was detected in the digestibility of acid detergent fibers(P>0.05).There were significant effects of forage combinations on gross energy intake(GEI),digestibility and metabolic rate of energy(P<0.05),and the methane energy/gross energy intake(CH4-E/GEI) of diet D was significantly lower than that of the other diets(P<0.05).There were no significant differences in the percentage of fecal nitrogen or urinary nitrogen in total nitrogen intake among different diets(P>0.05).Nitrogen digestibility of diet D was significantly higher than that of the diet B and diet C(P<0.05),and that of diet B was also significantly higher than that of diet A(P<0.05);meanwhile,nitrogen utilization of diet D and diet B was significantly higher than that of diet A(P<0.05).In conclusion,nutrient digestibility,utilization of nitrogen and energy of the diet compounded with corn silage,alfalfa hay and Chinese wildrye are better than those of diet with the other combinations,and there are positive combination effects between corn stover and Chinese wildrye,which can improve nutrient digestibility and utilization of energy and nitrogen.