Effects of potassium carbonate and sodium bicarbonate on rumen function in lactating Holstein cows

Twelve multiparous lactating Holstein cows were used to compare effects of 1) no buffer, 2) 1.5% sodium bicarbonate, 3) 1.25% potassium carbonate, or 4) 1.85% potassium carbonate in total diet on rumen environment and liquid turnover, dry matter intake and digestibility, milk yield and composition, and blood acid-base balance. Cows fed buffered diets had greater dry matter intake and greater digestibility of dry matter, acid detergent fiber, and neutral detergent fiber than controls. Rumen pH was higher in cows fed buffers than in controls 2 to 4 h postfeeding, but buffered diets were not different. Rumen volume, osmolality, and liquid turnover were unaffected by dietary treatment. Molar percentage of rumen acetate was greater, propionate was less, and acetate:propionate ratio was greater in cows fed 1.85% potassium carbonate compared with other treatments. There were no treatment effects on milk yield, although milk fat percentage tended to be greater in buffered diets. Blood acid-base balance was not altered. Cows fed diets containing potassium carbonate performed similarly to those fed sodium bicarbonate. No adverse effects of potassium carbonate on rumen function or environment were observed. Potassium carbonate is an acceptable buffer and serves as a potassium supplement.