effects of monensin supplementation alone or in combination with methafix on milk production and composition, ruminal parameters and serum metabolites of lactating dairy cows

this study was conducted to evaluate the effects of inclusion of monensin alone or in combination with methafix (a commercial product containing malate and fumarate) in the diets of lactating dairy cows on ruminal parameters and serum metabolites. four multiparous holstein lactating dairy cows (657± 12 kg of live weight; 133 ± 41days in milk) were assigned to one of the four dietary treatments. the first treatment was the control diet(c), second was control diet supplemented with 24 mg of monensin/kg of dm (m), the third was control diet supplemented with 5 g of methafix/kg dm (me) and the fourth treatment was c diet supplemented with 24 mg of monensin in combination with 5 g of methafix/kg dm (mm). dietary supplementation with monensin alone or in combination with metafix significantly decreased dry matter intake (p