A Meta-analysis of the Metabolic Impacts of Monensin in Lactating Dairy Cattle

Abstract

Monensin shifts the microbial population in the rumen towards more gram negative bacteria, consequently changing rumen volatile fatty acid concentrations towards propionate and away from acetate and butyrate. Since the late 1980's there have been many papers published on the effects of monensin in lactating dairy cattle. Recently, approvals for use on monensin have been obtained in Canada and the United States, while the product has been available for dairy cattle in countries such as Mexico, Australia and New Zealand for many years. The impacts of monensin on energy metabolism, including effects on serum ketones, NEFA, glucose, and urea have not always been consistent. Meta-analysis is a useful tool that can be employed to both summarize effects across studies and to investigate factors explaining potential heterogeneity of response.