燕麦干草与全株玉米青贮不同组合对绵羊瘤胃发酵的影响

本试验旨在明确燕麦干草与全株玉米青贮按不同比例组合对绵羊瘤胃发酵的影响。选用9头体重为(70.24±2.03)kg、体况相似且装有永久性瘤胃瘘管的杂种(美利奴×蒙古羊♀)公羊作为试验动物,按过渡期称重结果分成3组,每组3只。按燕麦干草和全株玉米青贮占粗饲料比例(干物质基础)将饲粮分为A1(100%全株玉米青贮)、A2(50%全株玉米青贮+50%燕麦干草)和A3(100%燕麦干草)3种,3种饲粮精粗比均为35∶65。采用3×3拉丁方设计,进行3期试验,每期22 d(预试期15 d,正试期7 d),正试期最后3 d采样。结果显示:1)与100%全株玉米青贮相比,以50%全株玉米青贮+50%燕麦干草或100%燕麦干草为粗饲料对绵羊瘤胃液p H和总氮浓度平均值没有产生显著影响(P0.05),但显著降低了瘤胃液氨态氮(NH3-N)、尿素氮和血浆尿素氮浓度平均值(P0.05),同时以50%全株玉米青贮+50%燕麦干草为粗饲料还显著提高了瘤胃液蛋白氮浓度平均值(P0.05)。此外,A2组的瘤胃液p H和总氮浓度平均值稍高于A3组,瘤胃液蛋白氮浓度平均值较A3组增加了8.97%,瘤胃液和血浆尿素氮浓度平均值稍低于A3组,但差异均不显著(P0.05),而瘤胃液NH3-N浓度平均值则显著低于A3组(P0.05)。2)粗饲料中燕麦干草的加入并未显著改变绵羊瘤胃液总挥发性脂肪酸浓度和丙酸摩尔比平均值(P0.05),升高了瘤胃液乙酸、丁酸摩尔比以及乙酸/丙酸平均值,且A3组与A1组差异显著(P0.05)。由此可知,在精料相同、精粗比为35∶65的条件下,用50%全贮玉米青贮和50%燕麦干草混合作为粗饲料可以改善绵羊的瘤胃内环境而适宜瘤胃微生物生长,提高瘤胃微生物活性及其对氨(NH3)的利用率,有助于微生物蛋白的合成,升高瘤胃乙酸的摩尔比及乙酸/丙酸。

Effects of Different Combinations of Oat Hay and Whole Corn Silage on Ruminal Fermentation of Sheep

This experiment was conducted to investigate the effects of different combinations of oat hay and whole corn silage on ruminal fermentation of sheep. Nine cross breed ( Merino×Mongolian) rams with similar body condition, body weight of (70.24±2.03) kg and fitted with permanent rumen cannulas were selected and divided into three groups with three sheep per group according to the weighting result of transitional period, and their diets were grouped as three according to the ratio of oat hay and whole corn silage in the roughage ( dry matter basis) , i. e. , A1 ( 100% whole corn silage ) , A2 ( 50% oat hay+50% whole corn silage ) and A3 (100% oat hay), and the concentrate?to?forage ratio of three diets was 35:65. A 3×3 Latin square design was used. Three trial periods were conducted with 22 days for each period ( 15 days for pretest and 7 days for for?mal test) . Samples were taken at the last 3 days of the formal test. The results showed as follows:1) compared with 100% whole corn silage, taking 50% oat hay+50% whole corn silage or 100% oat hay as roughage had no significant effects on pH and total nitrogen concentration in ruminal fluid, but significantly reduced the means of ruminal fluid urea nitrogen, ammoniacal nitrogen ( NH3?N) , and plasma urea nitrogen concentrations ( P<0.05); in the meantime, taking 50% oat hay+50% whole corn silage as roughage significantly increased the mean of protein nitrogen concentration in ruminal fluid ( P<0.05) . Besides, compared with A3 group, A2 group had slightly higher the means of ruminal fluid pH and total nitrogen concentration, lower ruminal fluid and plasma urea nitrogen concentration means, and its ruminal fluid protein nitrogen concentration mean in?creased by 8.97%, but no significant differences in above indices were found ( P>0.05) . The mean of ruminal fluid NH3?N concentration in A2 group was significantly lower than that in A3 group (P<0.05). 2) Adding oat hay in diet did not change the mean of ruminal fluid total volatile fatty acid concentration and propionic acid molar ratio, but increased the mean of ruminal fluid acetate acid, butyric acid molar ratios and acetate/propio?nate ( P<0.05) , and those in A3 group were significantly higher than those in A1 group ( P<0.05) . In conclu?sion, base on the same concentrate and the concentrate?to?forage ratio of 35:65, mixing 50% oat hay with 50%whole corn silage in sheep diet can improve rumen environment, microbe growth and activity, increase ammo?nia (NH3) utilization, help microbe protein synthesis, and also increase acetate acid molar ratio and acetate/propionate.