Effects of cellulase and Lactobacillus plantarum on fermentation quality, microbial diversity, gene function prediction, and in vitro rumen fermentation characteristics of Caragana korshinskii silage

The study aimed to investigate the effects of cellulase and Lactobacillus plantarum on fermentation quality, microbial diversity, gene function prediction, and in vitro rumen fermentation parameters of Caragana korshinskii silage. The experimental treatments included control (CK), cellulase (C), Lactobacillus plantarum (L), and cellulase+Lactobacillus plantarum (CL). Triplicate sacks were sampled after 14 and 56 days of silaging, respectively. The microbial diversity of the Caragana korshinskii silage was analyzed by high-throughput sequencing technology, and 16S rRNA gene prediction function profiles were analyzed using Tax4Fun according to the Kyoto Encyclopedia of Genes and Genomes (KEGG) on day 56. Moreover, the effects of Caragana korshinskii silage on rumen fermentation were evaluated using the in vitro artificial rumen gas production method. The results showed that the used additives could reduce the content of ammonia nitrogen, neutral detergent fiber, and acid detergent fiber during silaging. Compared with CK, higher lactic acid content was observed in the silages treated with C and L but with a higher acetic acid content in CL. After 56 days of silage, Compared with CK, Lactobacillus in other groups was significantly increased but Enterococcus, Weisseria, Enterobacter, and Pediococcus were significantly decreased (except C). The results of gene function prediction showed that the metabolism of carbohydrates, transport, nucleotide and amino acid were the highest in silage. The enzymes involved in lactate production are pyruvate kinase, 1-phosphofructokinase, and fructokinase. The high acetic acid content in CL may be related to the 6-phosphate glucose dehydrogenase. The H+-transporting ATPase and ABC transporters in L and CL were higher than that of CK, indicating that L and CL had stronger membrane transport ability. The results of in vitro rumen fermentation test showed that compared with CK, L and CL increased gas production and the digestibility of in vitro dry matter and neutral detergent fiber. In conclusion, the addition of cellulase and Lactobacillus plantarum can improve the fermentation quality, increase nutrient digestibility, and alter the microbial diversity and specific functional metabolites in Caragana korshinskii silage. The addition of cellulase + Lactobacillus plantarum gave better results, which could provide a theoretical basis for improving the quality of silage.