Monensin Alters the Functional and Metabolomic Profile of Rumen Microbiota in Beef Cattle

Abstract

Simple SummaryMonensin can enhance the efficiency of feed utilization by modulating rumen fermentation; however, its effects on rumen function has not been fully described. Thus, this study integrated metagenomics and metabolomics analysis to identify differences in functional attributes and metabolites of rumen microbiota in beef steers fed no or 200 mg/d of monensin. Our results showed differences in relative abundance of functional genes involved in lipid metabolism and amino acid metabolism as well as changes in rumen fluid metabolites and their metabolic pathways. This study revealed a better understanding of the effects of monensin, which may enable more effective use of this additive for beef cattle production.AbstractTo identify differences in rumen function as a result of feeding monensin to beef cattle, rumen fluid metagenomics and metabolomics analyses were used to evaluate the functional attributes and metabolites of rumen microbiota in beef steers fed no or 200 mg/d of monensin. Eight rumen-fistulated steers were used in the study for a period of 53 days. Rumen fluid samples were collected on the last day of the experiment. Monensin increased the relative abundance of Selenomonas sp. ND2010, Prevotella dentalis, Hallella seregens, Parabacteroides distasonis, Propionispira raffinosivorans, and Prevotella brevis, but reduced the relative abundance of Robinsoniella sp. KNHs210, Butyrivibrio proteoclasticus, Clostridium botulinum, Clostridium symbiosum, Burkholderia sp. LMG29324, and Clostridium butyricum. Monensin increased the relative abundance of functional genes involved in amino acid metabolism and lipid metabolism. A total of 245 metabolites were identified. Thirty-one metabolites were found to be differentially expressed. Pathway analysis of the differentially expressed metabolites revealed upregulated metabolic pathways associated with metabolism of linoleic acid and some amino acids. These findings confirm that monensin affects rumen fermentation of forage-fed beef cattle by modulating the rumen microbiome, and by reducing amino acid degradation and biohydrogenation of linoleic acid in the rumen.

Integrating 16S rRNA Sequencing and LC–MS-Based Metabolomics to Evaluate the Effects of Live Yeast on Rumen Function in Beef Cattle

“…The samples were prepared according to procedures described by Ogunade et al [13]. Briefly, 500 µL of the ruminal fluid sample was mixed with 2 mL of methanol–water (1:1, v / v ) and then vortex-mixed for 2 min.…”

“…However, alterations in the types of metabolites produced as a result of feeding yeast additives have not been completely described. Recent studies have applied metabolomics, the comprehensive analysis of all metabolites in a biological system, to predict feed efficiency [9,10], evaluate dietary responses to different feeds [11], assess the milk quality of ruminants [12], and evaluate the effect of monensin on the rumen microbial population [13]. However, no studies have applied metabolomics to study the effects of live yeast additives.…”

Natural Oregano Essential Oil May Replace Antibiotics in Lamb Diets: Effects on Meat Quality

“…The similarity between SM and MO might imply that as they modify the rumen environment, the growth rate of rumen microflora changes, resulting in changes in the fermentation profile [49,55,78]. These changes impact the fatty acid profile [79], as it has been reported that monensin was at least partially effective to inhibit the biohydrogenation of unsaturated FAs in the rumen. This consequently increased the percentage of n-6 and n-3 PUFAs and conjugated linoleic acid in milk.…”

“…Therefore, the concentration of propionic and butyric acids increase, while acetate decreases in ruminal fluid. This leads to an acetate:propionate ratio decline [3,[84][85][86], which in turn favours the recovery of energy used by the animal [79]. Additionally, SM reduces the formation of methane and lactic acid produced by other microorganisms [87,88].…”

Metatranscriptomic Analysis of Sub-Acute Ruminal Acidosis in Beef Cattle

“…The solid and liquid fractions were mixed 1:1 ( w / w ) to ensure equal proportions of solid and liquid fractions, and the fractions were stored at −80 °C until metatranscriptomic analysis was done. In addition, subsamples of the liquid fractions were taken and analyzed for volatile fatty acids (VFA) and lactate as described by Ogunade et al [11]. Briefly, 12 µL of 50% H 2 SO 4 were added to 12 mL of the liquid portion of ruminal content.…”