PSII-21 - Effects of dietary supplementation with sucrose on in vitro ruminal fermentation and bacterial composition

Abstract: Carbohydrate is the main energy source in ruminants, and plays a crucial role in maintaining animal growth, body metabolism and production performance. Sucrose is one of the important carbohydrate source of dairy cows, has primary impact on energy utilization efficiency, production performance and gastrointestinal tract health. The experiment assigned to 5 groups supplying different concentrations of sucrose: 0% (CON), 2%, 4%, 6% and 8%. Six fermentation time points of 0.5, 1, 2, 3, 6 and 48 h were see, each time group had 5 replicates. Gas production parameters, the volatile fatty acids (VFAs), pH, ammonia nitrogen (NH3-N) and rumen microbiome in fermentation fluid were analyzed. The results indicated that the 6% and 8% sucrose groups significantly increased the total gas production, the maximum gas production rate (RmaxG), the maximum degradation rate of substrate (RmaxS) and the average gas production rate when half of the ideal maximum gas production produced (AGPR) compared with CON group at 48 h (P < 0.05), while the 8% group had significant reduction in pH (pH = 6.47). The supplementation of sucrose decreased the content of NH3-N (P < 0.05), and the 6% and 8% groups significantly decreased the ratio of acetate and propionate (P < 0.05), but VFAs had no differences between the five groups (P > 0.05). With the increase of sucrose, alpha diversity index had no significant difference between the sucrose supplementation groups and CON group (P > 0.05), Prevotellaceae, xylanophilum_ Group, Pseudocardovia, Marvinbryantia were significantly enriched in 8% group (P < 0.05, LDA score > 2). In comprehensive result of gas production parameters, NH3-N and microbial composition analysis, the appropriate amount of sucrose is 8% (% of dry matter) under our experimental conditions.