Open AccessDosage‐dependent effects of monensin on the rumen microbiota of lactating dairy cattle
Author(s) -
McGarvey Jeffery A.,
Place Sara,
Palumbo Jeffrey,
Hnasko Robert,
Mitloehner Frank
Publication year - 2019
Publication title -
microbiologyopen
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.881
H-Index - 36
ISSN - 2045-8827
DOI - 10.1002/mbo3.783
Subject(s) - monensin , rumen , biology , dose , dairy cattle , 16s ribosomal rna , zoology , bacteria , microbiology and biotechnology , food science , fermentation , genetics , pharmacology
We examined the dose‐dependent effects of feeding lactating dairy cows a standard diet supplemented with monensin at 175, 368, or 518 mg cow ‐1 day ‐1 on the rumen microbiota. For each dosage, 3 animals were randomly assigned into groups and fed the same basal total mixed ration diet supplemented with monensin, at the respective dose. After 20 days, rumen samples were taken and the effect on the microbiota was examined by 16S rRNA gene sequence analysis and qPCR. At the lowest dose no significant change in 16S rRNA gene sequences associated with any bacterial phyla was observed; however, at the medium and high dosages, we observed significant reductions in sequences associated with gram‐positive bacteria and significant increases in those associated with gram‐negative bacteria that were dosage dependent. All dosages reduced the levels of sequences associated with methanogenic archaea in the rumen, with the medium dosage showing the largest decline. No significant difference was observed for the 18S rRNA gene sequences associated with protozoa in any of the libraries. Our results indicate that with this diet the medium dosage of monensin was most efficacious for the reduction in methanogenic archaea in the rumen of lactating dairy.