|McGarvey, Jeffery - Jeff|
|PLACE, SARA - United States Cattlemen'S Association|
|Palumbo, Jeffrey - Jeff|
|MITLOEHNER, FRANK - University Of California, Davis|
Submitted to: Advances in Dairy Research
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 8/10/2018
Publication Date: 8/14/2018
Citation: McGarvey, J.A., Place, S., Palumbo, J.D., Hnasko, R.M., Mitloehner, F. 2018. Dosage-dependent effects of Monensin on the rumen microbiota of lactating dairy cattle. Advances in Dairy Research. 8(7):e00783. https://doi.org/10.1002/mbo3.783.
Interpretive Summary: We investigated the dosage effects of the drug monensin on the microbes that reside in the cow stomach. We observed a dose dependent change in the types of bacteria present in the stomach. The results of these studies demonstrate how the growth promoting antibiotic monensin affects the types of bacteria in the cow stomach.
Technical Abstract: 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-1on 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.