Classified as a "buffer" for improvement of milk fat percentage.   Site of action in the cow is in the Rumen where bentonite swells 5 to 20 times which increases rumen pH and slows turnover, therefore increasing acetate to propionate ratio.

Sodium bicarbonate is employed in dairy feeding to neutralize acids produced during rumen fermentation of feedstuffs and thus, maintain a rumen pH more conducive to optimum fiber digestion and microbial protein synthesis. Bicarbonate is only a rumen buffer and has no effect on intestinal pH. Reasons for feeding are: (1) prevent milk fat depression or correct an existing depression, and (2) increase dry matter intake, especially when acidic diets are fed.

Magnesium has been reported to increase milk fat percentage. Mode of action is unknown but addition of magnesium to fat depressing diets increases lipoprotein lipase, the enzyme responsible for transferring of fat from blood to organs, in the mammary gland.