Effect of Feeding Buffers to Dairy Cows Fed a High-Concentrate, Low-Roughage Ration

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Abstract
Eight lactating cows were grouped and assigned to one of two 4x4 Latin squares. Cows were offered concentrates ad libitum and 2 lb of hay daily. The 4 treatments consisted of an unsupplemented control ration, 1.00 lb KHCO3, 0.84 lb NaHCO3 and 0.42 lb MgCO3 per day. The addition of any one of the buffers prevented the depression to milk fat test that occurred while the cows were on the control ration (2.92 vs 3.62%). Cows while on the control ration had an average daily gain in body weight of 2.46 lb per day, which was greater (P < .01) than the average of 0.04 lb while on the buffered rations. When the control ration was fed, cows had a lower (P< .05) M% of rumen acetic acid (49.2 vs 54.0), higher (P<.05) M % of propionic acid (37.4 vs 31.3) and n-valeric acid (2.8 vs 1.8) than when fed the buffered rations. Rumen pH and Eh were not significantly affected by ration.