Effects of Rumen-Mate on lactational performance of Holsteins fed a high grain diet.

Three Latin-square trials were conducted to determine the effects of supplementing Rumen-Mate, a commercial buffer containing KCl, NaCl, and Mg and Na carbonates, on lactation performance of Holsteins. Cows were fed a basal ration of 40% corn silage and 60% concentrate in Trials 1 and 2, and 40% corn silage, 55% concentrate, and 5% alfalfa hay in Trial 3 (DM basis). In Trial 1, treatments were: basal diet, or basal diet supplemented with either 1% NaHCO3, or 1, 3, or 4.4% Rumen-Mate. Increasing dietary Rumen-Mate resulted in a linear increase in milk fat production and concentration with no difference between 1% Rumen-Mate and 1% bicarbonate. There was a significant linear decrease in milk protein concentration, but not production, with increasing concentrations of Rumen-Mate. In Trial 2 treatments were: basal diet, or basal diet supplemented with either .8% NaHCO3, 2.6% Rumen-Mate, .5% MgO, .8% NaHCO3 plus .5% MgO, or 1.8% Rumen-Mate plus .8% NaHCO3. Organic matter and CP intakes and milk protein yield and concentration were decreased by Rumen-Mate with a nonsignificant increase in milk fat concentration. Data from Trials 1 and 2 were combined with data from Trial 3, which compared basal diet, 1% bicarbonate, and 3% Rumen-Mate. The combined data showed a larger increase over basal diet in milk fat yield and concentration for 2.6 to 3% Rumen-Mate vs. .8 to 1% bicarbonate. Rumen-Mate did not decrease DM intake or protein yield relative to basal diet but did decrease protein yield 34 g/d compared with that of bicarbonate.

Effects of sodium bicarbonate or sodium sesquicarbonate on lactating Holsteins fed a high grain diet.

Fifteen Holstein cows, 35 to 70 d postpartum, were assigned to five 3 x 3 Latin squares. Treatments were: control (60% concentrate, 40% corn silage, DM basis) or control supplemented with either .71% sodium bicarbonate or .65% sodium sesquicarbonate, DM basis. Orthogonal contrasts compared the effect of both buffered diets versus the control diet, and the effect of sodium bicarbonate supplementation vs. sodium sesquicarbonate supplementation. There were no differences among treatments for milk yield (34.9 kg/d), milk fat yield (.99 kg/d), 3.5% FCM (31.1 kg/d), or milk protein concentration (3.15%). There were no treatment effects on total chewing time. Milk fat concentration tended to be greater for cows fed sodium bicarbonate (2.92%) and sodium sesquicarbonate (2.89%) relative to control (2.82%). Relative to control, sodium bicarbonate and sodium sesquicarbonate supplementation increased DM intake (22.0 and 22.7 vs. 21.4 kg/d), digestible DM intake (16.7 and 16.2 vs. 14.8 kg/d), digestible organic matter intake (16.0 and 15.5 vs. 14.3 kg/d); and apparent digestibility of DM (77.3 and 74.8 vs. 73.3%) and NDF (62.6 and 56.5 vs. 54.7%). Relative to sesquicarbonate, bicarbonate supplementation increased apparent digestibilities of CP (82.3 vs. 78.8%) and NDF, and decreased milk protein yield (1.06 vs. 1.11 kg/d). Sesquicarbonate was as effective as bicarbonate in alleviating milk fat depression and increasing intake of digestible organic matter.