日粮不同能量和蛋白质水平对生长期牦牛瘤胃发酵参数及瘤胃菌群的影响

Effect of Different Dietary Energy and Protein Levels on Rumen Fermentation Parameters and Rumen Microflora in Growing Yaks

为研究日粮不同能量和蛋白质水平对生长期牦牛瘤胃发酵参数及瘤胃菌群的影响,选取体重、体况相近且健康的1.5周岁娘亚牦牛48头,采用3×2双因素试验设计,按不同综合净能(7.63、8.25、8.88 MJ/kg)和蛋白质(10.84%、12.82%)水平随机分为6组,每组8个重复(公母各半),每个重复1头牛。预试期15 d,正试期60 d。结果表明:(1)瘤胃液中,高能量组的乙酸摩尔百分比显著高于中能量组(P <0.05),中能量组的丙酸摩尔百分比显著低于高、低能量组(P <0.05),而丁酸摩尔百分比显著高于高、低能量组(P <0.05);高蛋白质组的异丁酸和异戊酸摩尔百分比显著高于低蛋白质组(P <0.05);日粮能量与蛋白质水平的交互作用对异丁酸、异戊酸和戊酸摩尔百分比有显著影响(P <0.05)。(2)瘤胃菌群中,低能量和中能量组的Chao1和Shannon指数显著高于高能量组(P <0.05);低蛋白质组的Chao1和Shannon指数显著高于高蛋白质组(P <0.05);日粮能量与蛋白质水平的交互作用对Chao1和Shannon指数有显著影响(P <0.05)。(3)中能量组鸢尾花菌门(Kiritimatiellaeota)的相对丰度显著高于低能量组(P <0.05);日粮能量与蛋白质水平的交互作用对厚壁菌门(Firmicutes)、拟杆菌门(Bacteroidete)、互养菌门(Synergistetes)和变形菌门(Proteobacteria)相对丰度有显著影响(P <0.05)。高能量组细菌F082的相对丰度显著高于低能量组和中能量组(P <0.05),中能量组理研菌科RC9肠道群(Rikenellaceae_RC9_gut_group)的相对丰度显著高于高能量组(P <0.05);高蛋白质组细菌F082的相对丰度显著高于低蛋白质组(P <0.05),拟杆菌目RF16群(Bacteroidales_RF16_group)的相对丰度显著低于低蛋白质组(P <0.05);日粮能量与蛋白质水平的交互作用对克里斯滕森菌科R-7群(Christensenellaceae_R-7_group)、细菌F082和瘤胃球菌科NK4A214群(Ruminococcaceae_NK4A214_group)的相对丰度有显著影响(P <0.05)。综上所述,当生长期牦牛的日粮综合净能为8.25 MJ/kg、蛋白质为12.82%时,更有利于促进瘤胃发酵,改善瘤胃菌群环境。

This experiment was conducted to investigate the effects of different dietary energy and protein levels on rumen fermentation parameters and rumen microflora in growing yaks.Forty-eight 1.5-year-old Niangya yaks with similar body weight and body condition were randomly divided into 6 groups with 8 replicates per group(half male and half female),and 1 yak per replicate according to different levels of comprehensive net energy(7.63,8.25,8.88 MJ/kg)and protein(10.84%,12.82%)using a 3×2 two-factor design.The pre-expriment period was 15 days,and the formal expriment period was 60 days.The results showed as follows:①In rumen fluid,the molar percentage of acetic acid in high energy group was significantly higher than that in medium energy group(P<0.05),the molar percentage of propionic acid in medium energy group was significantly lower than that in low energy and high energy groups(P<0.05),and the molar percentage of butyrate was significantly higher than that in low energy and high energy groups(P<0.05).The molar percentage of isobutyric acid and isovalerate in high protein group were significantly higher than those in low protein group(P<0.05).The interaction of dietary energy and protein levels had significant effects on the molar percentage of isobutyric acid,isovalerate and valerate(P<0.05).②In rumen microflora,Chao1 and Shannon indices in low and medium energy groups were significantly higher than those in high energy groups(P<0.05).Chao1 and Shannon indices in low protein group were significantly higher than those in high protein group(P<0.05).The interaction of dietary energy and protein levels had significant effects on Chao1 and Shannon indices(P<0.05).③The relative abundance of Kiritimatiellaeota in medium energy group was significantly higher than that in low energy group(P<0.05).The interaction of dietary energy and protein levels had a significant effect on the relative abundance of Firmicutes,Bacteroidete,Synergistetes and Proteobacteria(P<0.05).The relative abundance of bacteria F082 in high energy group was significantly higher than that in low and medium energy groups(P<0.05),and the relative abundance of Rikenellaceae_RC9_gut_group in medium energy group was significantly higher than that in high energy group(P<0.05).The relative abundance of bacteria F082 in high protein group was significantly higher than that in low protein group(P<0.05),and the relative abundance of Bacteroidales_RF16_group was significantly lower than that in low protein group(P<0.05).The interaction of dietary energy and protein levels had significant effects on the relative abundances of Christensenellaceae_R-7_group,bacteria F082 and Ruminococcaceae_NK4A214_group(P<0.05).In conclusion,when the dietary energy and protein levels were 8.25 MJ/kg and 12.82%,respectively,it is beneficial to promote rumen fermentation and improve rumen flora environment of growing yaks.