Alleviated nutrient imbalance by monensin premix (Romensin®, Rumensin®)

Reduced risk of ketonaemia in dairy cows

Abstract

In a European series of studies, the effects of administering monensin premix (Romensin^®, Rumensin^®) to dairy cows via the feed were examined. A total of 365 cows received either 0 or 300 mg monensin per cow per day from approximately one month post calving onwards. Blood samples were examined for ketone levels (beta-hydroxybutyrate and acetoacetate). Cows were categorized for ketonaemia risk by using their average ketone levels for up to five months of treatment. Mean ketone levels of or below 1.0 mmol/1 were considered to indicate normal values. Cows with normal ketone values were categorized into three groups: low normal (≤.50 mmol/1), medium normal (>0.50 to ≤0. 75 mmol/1) and high normal (>0. 75 to ≤1.00 mmol/1). Ketone levels above 1.00 mmol/1 were considered to indicate a ketonaemic condition. Cows treated with monensin were approximately twice as likely to occur in the lowest normal risk category and were approximately half as likely to occur in the highest normal category than control animals. Five percent of the control cows were found in the ketonaemic condition category versus one percent of cows which had received monensin. The difference between the two groups was significant (p<0.001).

These findings were most likely caused by the effects of monensin on rumen fermentation, increasing the production of propionic acid and increasing the supply of glucogenic nutrients derived from the ration. In these studies, monensin apparently alleviated nutrient imbalance and reduced the risk of ketonaemia in dairy cows during early lactation.