The Use of Sodium Bicarbonate in Complete Rations for Lactating Cows

Sixty-two Holstein cows were assigned to respective treatments of a randomized complete block design three days postpartum. Complete rations, formulated to meet NRC requirement, were fed during the first 112 days of lactation. Diets contained, on an as-fed basis, 75% corn silage and 25% pelleted concentrate (CS:PC) or (CS:PC) + .5% feed grade sodium bicarbonate added as a percent of the total ration (CS:PC+). In addition, each cow received 5 lb of alfalfa-grass hay daily (as fed).

Data collected weekly included milk yield (1b/d), milk fat (percent), 4% fat corrected milk (1b/d), ration dry matter intake (percent of body weight), and total dry matter intake (percent of body weight). Least-square means values of these parameters were 62.76, 3.30, 56.26. 2.09, 2.44, and 60.91, 3.42, 55.66, 2.19, 2.55 for CS:PC and CS:PC+, respectively. Significant treatment differences were not observed between diets (P > .05). Rumen fluid, blood, and additional milk samples were collected at monthly intervals from 27 cows randomly chosen from the total. Acetate-to-proportionate ratio and rumen pH values were 2.85, 6.45, and 2.66, 6.31 for CS:PC and CS:PC+, respectively. Blood serum Ca, P, Mg and Na values (mg/100 ml) were 9.44, 5.25, 2.22, 403.13, and 10.09, 5.40, 2.14 405.37 for CS:PC and CS:PC+, respectively. Least-square mean values for milk protein (percent), total solids (percent), and solids-not-fat (percent) were 3.95, 12.13, 8.87, and 3.98, 11.93, 8.53 for CS:PC and CS:PC+, respectively. No significant differences could be attributed to diets on data collection monthly (P > .05).

Results of this study indicate that incorporation of .5% sodium bicarbonate to complete rations was neither efficacious nor detrimental to dairy cows in early lactation.