Effects of 1.2% Sodium Bicarbonate with Two Ratios of Corn Silage:Grain on Milk Production, Rumen Fermentation, and Nutrient Digestion by Lactating Dairy Cows

Abstract

Four multiparous Holstein cows in mid lactation fitted with rumen cannulae were in a 4 × 4 Latin square experiment to study the effects of sodium bicarbonate and ratio of corn silage:grain on milk production and composition, feed intake, rumen fermentation, and nutrient utilization. Cows were fed diets of 50:50 or 75: 25 corn silage:grain with 0 or 1.2% sodium bicarbonate. Experimental periods were 21 days with 15 days for adaptation to diet and 6 days for data collection.Milk fat percent and 4% fat-corrected milk production (kg/day) were higher for cows fed diets containing 1.2% sodium bicarbonate (3.69 and 23.1 versus 3.03 and 19.3). Sodium bicarbonate and ratio of corn silage:grain had no effect on dry matter intake. Rumen pH was higher 1 and 3h postfeeding with added sodium bicarbonate (5.64 versus 5.83). Sodium bicarbonate increased total volatile fatty acids (91 versus 105 mm/liter), increased molar proportions of acetate, butyrate, and isovalerate, and decreased propionate and valerate. Dry matter, organic matter, and neutral-detergent fiber digestibilities were higher for cows fed diets composed of 50% grain compared with diets with 25% grain. Acid-detergent fiber digestibility was increased by sodium bicarbonate (47.7 versus 52.9%). Protein digestibility and nitrogen utilization were not affected by added sodium bicarbonate or the ratio of forage:grain. In summary, sodium bicarbonate added at 1.2% of the total dry matter to diets containing 50:50 and 75:25 corn silage:grain increased milk fat percent, fat-corrected milk production, rumen acetate:propionate, and utilization of acid detergent fiber.