Effects of silage of oak leaves treated with different additives on rumen degradation rate and microbial community of Yanbian cattle in vitro fermentation

This experiment was conducted to study the effects of different additives on the rumen degradation rate and microbial community of Yanbian cattle treated with oak leaf silage via in vitro fermentation. Four Yanbian cows with an average weight of (443.3 ± 26.7) kg and permanent rumen tubes were selected as rumen fluid donors. The silage oak leaves were divided into the molasses group (M group), lactic acid bacteria group (LAB group), effective microorganisms (a mixed group generally including photosynthetic bacteria, yeast, lactic acid bacteria, and other beneficial bacteria; EM group), lime water group (LW group), lactic acid bacteria and molasses group (LAB-M group), and EM and molasses group (EM-M group) according to different fermentation additives, with three replicates in each group. After 48 h of in vitro fermentation, the neutral detergent fiber degradation rate, dry matter degradation rate, and crude protein degradation rate were calculated, and total bacterial DNA was extracted from rumen fluid for PCR amplification and high-throughput sequencing using an Illumina Hi-Seq 2500 sequencing platform. The results showed that the degradation rates of dry matter, crude protein, and neutral detergent fiber in each oak leaf silage test group were significantly higher than those in the control group (P < 0.05), and the degradation rates of the EM and EM-M groups exhibited the most significant increase. The dry matter, crude protein, and neutral detergent fiber degradation rates of the LW group were significantly lower than those of the other five groups ( P < 0.05). Silage oak leaves with different fermentation additives had no significant effects on the rumen microflora of Yanbian cattle via in vitro fermentation ( P > 0.05). At the phylum level, Proteobacteria, Bacteroidota, and Firmicutes were the main microbial flora in the rumen of ruminants. At the genus level, Acinetobacter, Prevotella, and Arcobacter were the main microbial flora. In conclusion, different additives can effectively improve the rumen degradation environment and rate. Among them, EM and EM-M groups had a better effect. All experimental groups had no adverse effects on the overall composition, microbial diversity, and microbial abundance in the rumen of Yanbian cattle.