Effects of live yeast on differential genetic and functional attributes of rumen microbiota in beef cattle

Abstract

Several studies have evaluated the effects of live yeast supplementation on rumen microbial population; however, its effect on differential microbial genes and their functional potential has not been described. Thus, this study applied shotgun metagenomic sequencing to evaluate the effects of live yeast supplementation on genetic and functional potential of the rumen microbiota in beef cattle. Eight rumen-cannulated Holstein steers were randomly assigned to two treatments in a cross-over design with two 25-day experimental periods and a 10-day wash-out between the two periods. The steers were housed in individual pens and fed 50% concentrate-mix and 50% red clover/orchard hay ad libitum . Treatments were (1) control (CON; basal diet without additive) and (2) yeast (YEA; basal diet plus 15 g/d of live yeast product). Rumen fluid samples were collected at 3, 6, and 9 h after feeding on the last d of each period. Sequencing was done on an Illumina HiSeq 2500 platform. Dietary yeast supplementation increased the relative abundance of carbohydrate-fermenting bacteria (such as Ruminococcus albus , R . champanellensis , R. bromii , and R. obeum ) and lactate-utilizing bacteria (such as Megasphaera elsdenii , Desulfovibrio desulfuricans , and D. vulgaris ). A total of 154 differentially abundant genes (DEGs) were obtained (false discovery rate < 0.01). Kyoto Encyclopedia of Genes and Genomes (KEGG) annotation analysis of the DEGs revealed that 10 pathways, including amino sugar and nucleotide sugar metabolism, oxidative phosphorylation, lipopolysaccharide biosynthesis, pantothenate and coenzyme A biosynthesis, glutathione metabolism, beta-alanine metabolism, polyketide sugar unit biosynthesis, protein export, ribosome, and bacterial secretory system, were enriched in steers fed YEA. Annotation analysis of the DEGs in the carbohydrate-active enzymes (CAZy) database revealed that the abundance of genes coding for enzymes belonging to glycoside hydrolases, glycosyltransferases, and carbohydrate binding modules were enriched in steers fed YEA. These results confirm the effectiveness of a live S. cerevisiae product for improving rumen function in beef steers by increasing the abundance of cellulolytic bacteria, lactic acid-utilizing bacteria, and carbohydrate-active enzymes in the rumen. Electronic supplementary material The online version of this article (10.1186/s40104-019-0378-x) contains supplementary material, which is available to authorized users.

Effects of Multi-Species Direct-Fed Microbial Products on Ruminal Metatranscriptome and Carboxyl-Metabolome of Beef Steers

“…To the best of our knowledge, this was the first study that attempted to investigate the effects of S. cerevisiae -based DFM on the relative abundance of transcriptionally active members and functional attributes of the rumen microbiota in beef cattle that were fed a corn silage-based diet. Several previous studies that evaluated the effects of S. cerevisiae -based DFM on rumen microbial population, focused on the taxonomic abundance of rumen microbial population [ 4 , 30 , 31 ]. In our companion study [ 7 ], we analyzed the effects of supplemental PROB and SYNB on the relative abundance of ruminal bacterial via 16S rRNA gene sequencing and observed that, compared to CON, supplemental PROB altered the relative abundance of Succinivibrio , Rikenellaceae RC9 gut group, Succiniclasticum , Prevotella 1, and Prevotellaceae UCG-001, whereas SYNB altered the relative abundance of Succinivibrionaceae UCG- 001, Succiniclasticum , Prevotella 1, and Prevotellaceae UCG-001.…”

“…Saccharomyces cerevisiae is capable of de novo biosynthesis of co-enzyme A, via the activities of dephospho-CoA kinase [ 38 ]. The results of our previous study [ 4 ] demonstrated that coenzyme A biosynthesis pathway was enriched in the rumen of beef steers fed diet supplemented with a S. cerevisiae -based additive. Thus, it is reasonable to infer that supplemental PROB and SYNB stimulated the conversion of succinate to propionate via biosynthesis of coenzyme A, which catalyzes the conversion of succinate to methylmalonyl-CoA and then to proponyl-CoA, which is subsequently converted to propionate [ 38 ].…”

“…On day 21 of each period, 150 mL of the ruminal contents were collected via the cannula at 1, 3, 6, 9, 12, and 18 h after feeding. A sample of the rumen content was manually homogenized, as described by previous studies [ 4 , 8 ]. In brief, the ruminal contents were hand-strained through 4 layers of cheesecloth to separate the solid and liquid fractions.…”

“…Several studies utilized culture-independent molecular techniques to study the modes of action of DFM products, which include shift in rumen microbial community and fermentation pattern [ 3 , 4 ]. Most of the studies that evaluated a microbial community shift focused primarily on relative microbial abundance in the rumen [ 4 , 5 ]. However, how DFM affects the functional activity (analyzed via metatranscriptomics) of the rumen microbiome is currently unknown.…”

Impact of inulin and yeast containing synbiotic on calves' productivity and greenhouse gas production

“…Ogunade et al . [ 45 ] stated that yeast S. cerevisiae at the dosage 15 g/day might increase the amount of ruminal CH 4 produced in steers in a 25-day long experiment due to the increased abundance of M. ruminantium . Ding et al .…”