复合菌发酵稻草对安格斯牛生长性能、瘤胃发酵参数及菌群结构的影响

Effects of Compound Bacteria Fermented Rice Straw on Growth Performance,Rumen Fermentation Parameters and Microbial Structure of Angus Cattle

本试验旨在研究复合菌发酵稻草对安格斯牛生长性能、瘤胃发酵参数以及菌群结构的影响。选择14月龄左右、体重[(390.47±50.14)kg]相近的健康安格斯牛20头,随机分为2组,每组10个重复,每个重复1头牛。稻草组(RS组)饲喂稻草+玉米青贮+精料全混合日粮,发酵稻草组(FRS组)饲喂发酵稻草+玉米青贮+精料全混合日粮,2组全混合日粮营养水平基本一致。预试期7 d,正试期93 d。结果表明:1)复合菌发酵稻草表面出现空鼓和开裂,纤维结构发生改变。相比稻草和发酵对照,复合菌发酵稻草的中性洗涤纤维(NDF)、酸性洗涤纤维(ADF)、玉米赤酶烯酮含量和霉菌总数下降,粗蛋白质(CP)含量和细菌总数提高,未检出黄曲霉毒素B 1和呕吐霉素。2)与RS组相比,FRS组的平均日增重和平均日采食量显著提高(P<0.05),料重比显著降低(P<0.05)。3)与RS组相比,FRS组的瘤胃微生物蛋白含量极显著提高(P<0.01),瘤胃pH和氨态氮、总挥发性脂肪酸、丁酸含量及乙酸/丙酸差异不显著(P>0.05)。4)与RS组相比,FRS组的Sobs指数显著提高(P<0.05),Ace指数和Chao指数极显著提高(P<0.01),Shannon指数有升高趋势(P=0.093),Simpson指数差异不显著(P>0.05)。5)门水平上,2组的优势菌门主要为厚壁菌门(Firmicutes)和拟杆菌门(Bacteroidetes)。FRS组的拟杆菌门相对丰度显著高于RS组(P<0.05),厚壁菌门相对丰度显著低于RS组(P<0.05)。属水平上,2组优势菌属均为瘤胃球菌属_2(Ruminococcus_2),RS组其余相对丰度高于5%的菌属依次为毛螺菌科_NK3A20群(Lachnospiraceae_NK3A20_group)、瘤胃球菌科_NK4A214群(Ruminococcaceae_NK4A214_group)、理研菌科_RC9肠道群(Rikenellaceae_RC9_gut_group)以及普雷沃氏菌属_1(Prevotella_1);FRS组依次为普雷沃氏菌属_1、理研菌科_RC9肠道群和毛螺菌科_NK3A20群等。其中,RS组毛螺菌科_NK3A20群相对丰度极显著高于FRS组(P<0.01)。由此可见,复合菌发酵能改变稻草纤维结构,提高营养价值,减缓霉变。饲喂复合菌发酵稻草能提高安格斯牛生长性能、改善瘤胃发酵环境以及增加微生物菌群多样性和丰富度,同时影响门和属水平的菌群结构。

This experiment was to investigate the effects of compound bacteria fermented rice straw on growth performance,rumen fermentation parameters and microbial structure of Angus cattle.Twenty healthy 14-month-old Angus cattle with similar body weight[(390.47±50.14)kg]were randomly divided into two groups with 10 replicates in each group and 1 cattle in each replicate.Cattle in rice straw group(RS group)were fed a rice straw+corn silage+concentrate total mixed ration,and cattle in fermented rice straw group(FRS group)were fed a fermented rice straw+corn silage+concentrate total mixed ration,the nutrient levels of two groups were basically the same.The pre-experimental period lasted for 7 days,and the experimental period lasted for 93 days.The results showed as follows:1)the compound bacteria fermented rice straw was found to be hollow and cracked in surface,and the fiber structure changed.Compared with rice straw and fermented control,the contents of neutral detergent fiber(NDF),acid detergent fiber(ADF)and zearalenone and total mold count were decreased,the crude protein(CP)content and total bacterial count were increased,and the aflatoxin B 1 and vomitoxin were not detected.2)Compared with RS group,the average daily gain and average daily feed intake of FRS group were significantly increased(P<0.05),and in feed to gain ratio was significantly decreased(P<0.05).3)Compared with RS group,the rumen microbial protein content of FRS group was significantly increased(P<0.01),and the pH and contents of ammonia nitrogen,total volatile fatty acids and butyrate acid and acetate/propionate in rumen were no significant difference(P>0.05).4)Compared with RS group,the Sobs index of FRS group was significantly increased(P<0.05),the Ace index and Chao index were significantly increased(P<0.01),the Shannon index showed an increasing trend(P=0.093),while the Simpson index was no significant difference(P>0.05).5)At the phylum level,the dominant phyla of two groups were Firmicutes and Bacteroidetes.The Bacteroidetes relative abundance of FRS group was significantly higher than that of RS group(P<0.05),and the Firmicutes relative abundance was significantly lower than that of RS group(P<0.05).On the genus level,the dominant genus of two groups was Ruminococcus_2,and the rest genera with relative abundance higher than 5%of RS group were Lachnospiraceae_NK4A214_group,Rumi-nococcaceae_NK4A214_group,Rikenellaceae_RC9_gut_group and Prevotella_1;and the rest genera with relative abundance higher than 5%of FRS group were Prevotella_1,Rik-enellaceae_RC9_gut_group,Lachnospiraceae_NK3A20_group and Ruminococcaceae_NK4A214_group etc.Among them,the Lachnospiraceae_NK3A20_group relative abundance of RS group was significantly higher than that of FRS group(P<0.01).In conclusion,compound bacteria fermentation can change the fiber structure of rice straw,improve the nutritional value,and slow down the mildew.Feeding compound bacteria fermented rice straw can improve the growth performance,improve rumen fermentation environment and increase microbial community diversity and richness of Angus cattle,and affect the microbial structure at phylum and genus levels.