Effect of mineral salts, carbachol, and pilocarpine on nutrient digestibility and ruminal characteristics in cattle.

Fifty percent concentrate diets containing 2% sodium bicarbonate, sodium chloride, or no additional mineral salts were fed at a rate of 86 g dry matter/kg body weight X 75/d to three barren Holstein cows fitted with ruminal fistulas in a 3 X 3 Latin square design. Dietary adaptation was 14 d followed by 4 d collection. Ruminal pH, liquid volume, liquid dilution rate, and particulate rate of passage were increased with dietary mineral salts. Six Holstein cows fitted with ruminal fistulas were administered .01 mg carbachol/kg body weight/d, .10 mg pilocarpine/kg body weight/d, or saline placebo via subcutaneous, osmotically controlled pumps in a replicated 3 X 3 Latin square design. Treatments were administered for a 14-d adaptation period followed by an 8-d collection period. Both carbachol and pilocarpine increased liquid dilution rate, particulate rate of passage, and percent cellulolytic bacteria, whereas liquid volume was reduced.