Effects of sodium bicarbonate and sodium sesquicarbonate on animal performance, ruminal metabolism, and systemic acid-base status.

Six rumen-fistulated lactating Holstein cows were arranged in a replicated 3 x 3 latin square design with 3-wk periods and offered diets containing concentrate and corn silage in a 60:40 ratio (DM basis). Treatments were: 1) basal diet, 2) basal diet with 1% NaHCO3, and 3) basal diet with 1% sodium sesquicarbonate. There were no differences among treatments in milk production, milk protein, or 3.5% FCM, but sodium sesquicarbonate increased milk fat percentage (3.89, 3.94, 4.06%) compared with that of the control. Rumen pH was higher for cows fed buffered diets than for control cows. Urine pH was higher for cows fed NaHCO3 diet than for those fed sodium sesquicarbonate and control diets. No differences were detected among treatment means for molar percentage of isobutyrate, isovalerate, or total VFA, Dietary sesquicarbonate addition increased molar percentage of acetate, decreased propionate, and resulted in a higher acetate:propionate ratio compared with the cows fed NaHCO3. However, molar percentage of butyrate and valerate decreased in cows fed sodium sesquicarbonate when compared with those fed the control diet. No differences among treatment means were detected for blood pH, pCO2, or HCO3.