Effect of buffer addition to high grain total mixed rations on rumen pH, feed intake, milk production, and milk composition.

Lactating Holstein cows (n = 56) were fed high grain TMR in three feeding experiments to determine the effects of two rumen buffers on feed intake, milk production, and milk composition. The basal diet in Experiment 1 was 40% grass silage, 12% whole cottonseed, and 48% concentrate with treatments of 1) control (no added buffer), 2) 1.5% of dietary DM as Alkaten, and 3) 1.5% of dietary DM as Rumen 8. In Experiment 2, diets consisted of 12% corn and sunflower silage, 20% whole cottonseed, and 68% concentrate with treatments as in Experiment 1. The diets in Experiment 3 were identical to those in Experiment 2, except that buffers were increased to 2.2% of dietary DM. The DMI was greater for cows fed buffered diets than control diets in Experiments 2 and 3. Milk production was unaffected by treatment. Milk fat percentage was unaffected by diet in Experiment 1 and averaged 3.8%. Milk fat depression was alleviated for cows fed buffered diets in Experiments 2 and 3. No differences in rumen fluid pH or molar percentage of VFA were significant among treatments.