Rumen buffer Stabilises rumen pH Reduces Acidosis risk Improves butter fat Rich in Calcium Will not ‘over buffer’. Ostrea’s unique physical and chemical characteristics make it an ideal rumen buffer. It has a large surface area, thanks to its complex honeycomb structure, that helps sustain a more consistent rumen pH. It also provides an excellent source of calcium. Ostrea is capable of binding two hydrogen molecules, which gives it twice the binding capacity of sodium bicarbonate, but will never over buffer.