Effect of Different Proteins and Carbohydrates Ratio on In Vitro Fermentation and Rumen Bacterial Communities

Abstract

This study compared and analyzed in ruminal in vitro fermentation and determined diversity of rumen microbes and identified the dominant microbial species by in vitro in the ratio of protein and carbohydrate. Each treatment was mixed with soybean and starch at a ratio of 0:0, 10:0, 7:3, 5:5, 3:7 and 0:10. Parameters of in vitro fermentation such as pH, NH3-N, biogenic amine (BA) concentration were analyzed at 48h while microbial communities were analyzed at 24h. pH value was the lowest in the 0:10 and highest in the 0:0 (control) at 48h. Total gas production was the highest in the 10:0 and lowest 0:0 at 48h of fermentation. The NH3-N concentration was highest in the 10:0 and lowest in the 0:10 at 48h. Total BA concentrations were detected highest in the 10:0, lowest in the 0:0 and the highest DNA concentration of histamine-forming bacteria was obtained from the 10:0. On the other hand pH, ammonia and BA concentration were comparatively lower in the high carbohydrate ratio. In DGGE (Denaturing Gradient Gel Electrophoresis) profiles of rumen bacterial 16S rDNA amplicons, bands of R2 and R4 strains dominated in high protein, and R7, R8 and R9 strains dominated in high carbohydrate treatments. As a result of analysis of sequence of these strains, R1 to R6 strains were identified as uncultured species isolated from rumen and R7 to R9 strains were identified as Selenomonas sp. It is concluded that high carbohydrate ratio is beneficial for the ruminal fermentation on the basis of in vitro fermentation and DGGE analysis.