瘤胃源酵母的分离筛选及其在不同精粗比饲粮中对瘤胃体外发酵的影响

Isolation and Characterization of Rumen Yeast and Its Effect on Rumen in vitro Fementation in Different Concentrate to Forage Ratios

本试验旨在分离筛选瘤胃源酵母菌添加至不同精粗比饲粮中,研究酵母菌对反刍动物瘤胃体外发酵的影响,为研制出防治亚急性瘤胃酸中毒(SARA)的微生态制剂提供菌株。抽取4头荷斯坦公牛和4只肉羊瘤胃液,使用麦芽汁琼脂培养基,通过分离筛选,测定乳酸利用率及生长曲线,18S rRNA鉴定,最终获得1株乳酸利用率较高、生长速率较快的酵母菌,即褶皱假丝酵母菌(Candida rugosa),命名为N09号酵母。采用体外模拟瘤胃发酵技术,试验饲粮精粗比分别为5:5、6:4、7:3,测定在不同精粗比饲粮中添加活菌数为3×10^8 CFU/mL的该酵母菌对瘤胃主要发酵参数的影响。结果表明:随着日粮精粗比的提高,产气量呈降低趋势,干物质降解率和微生物蛋白浓度呈升高趋势;在9、12、28、36 h时,精粗比为6:4和7:3组pH显著高于5:5组;3组发酵液氨态氮浓度差异不显著;总挥发性脂肪酸、乙酸、丙酸和丁酸浓度随时间延长呈上升趋势,乙酸/丙酸呈下降趋势。

The rumen-derived yeasts were isolated and screened,the effects of adding yeasts to different concentrate diets on the rumen in vitro fermentation of ruminants were studied,and strains were provided as the development of microecological preparations for controlling SARA.Four Holstein cows and four hybrid mutton sheep with permanent fistulas were selected in the experiment,and AGAR medium of malt juice was used.Through separation and screening,lactic acid utilization rate and growth curve determination and 18S rRNA identification,finally obtained a yeast with higher lactic acid utilization rate and a faster growth rate,Candida rugosa,named N09 yeast.The effects of yeast on rumen fermentation parameters of 3×10^8 CFU/mL live bacteria added different concentrate diets were studied by simulating rumen fermentation technology in vitro,ratio of concentrate to roughness of experimental diet were 5:5,6:4,and 7:3.The results showed that with the increase of diet ratio,the gas production decreased,the dry matter degradation rate and microbial protein concentration increased.At 9,12,28,and 36 h,the pH of the 6:4 and 7:3 groups was significantly higher than that of the 5:5 group;The concentrations of ammonia nitrogen have no significantly difference in three groups fermentation broths.The concentrations of total volatile fatty acids,acetic acid,propionic acid and butyric acid increased,and acetic acid/propionic acid showed a downward trend as the reaction time prolonged.The results can provide a reference for the prevention of SARA in the production of high-precision diets.