RESUMO
The purpose of this study was to explore the effects of Rice straw and King grass on apparent digestibility, ruminal bacterial, and fungus composition in buffaloes. Three ruminal fistulated buffaloes were used in a 3 × 2 Latin square design. The dietary treatments were king grass and straw hay. Experimental animals were kept in individual pens and concentrate was offered at 1 kg/d while roughage was fed ad libitum. Each period lasted for 15d, with the first 12d for an adaptation period, followed by a 3-day formal trial period. King grass has higher digestibility of protein. Rice straw has higher digestibility to cellulose. The results showed that when buffaloes were fed king grass and straw, Bacteroidetes were dominant in the rumen normal flora, but firmicutes were not. In addition, the results of this experiment suggest that increasing protein content in diets may be beneficial to increase the relative abundance of Proteobacteria. Similarly, higher dietary fiber content may be beneficial for increasing relative abundance of Prevotella and Staphylococcus. The dominant fungi in ruminal fluid 2 h after ingestion were aerobic fungi. These aerobic fungi most likely entered the rumen with food. Whether and how long aerobic fungi can survive in the rumen needs more research.