Managing the risk of ketosis

The current unavailability of monensin bolus, a valuable tool for managing the risk of ketosis, may pose challenges for some farmers.

Monensin achieves its effect by increasing propionic acid production in the rumen. This was previously believed to be a consequence of a greater effect of monensin on Gram-positive bacteria than on Gram-negative bacteria. It has recently been shown that this is not the case, but rather that feed-carbohydrate-degrading bacteria, including Gram-negatives, have a greater adaptability to monensin than others (Guo et al, 2022). Propionic acid is converted in the liver of ruminants to glucose. No other volatile fatty acids are converted to glucose. Increasing the production of glucose and its concentration in the blood reduces excess fat mobilisation, thus reducing the incidence of ketosis. These effects explain why monensin reduces the risk of ketosis, displaced abomasum, and mastitis. In one study, it has also been found to increase milk yield (Mammi et al, 2021).