Before calving, cows are fed diets high in fiber. After calving, their requirements increase rapidly and their diet contains an increased amount of easily fermentable carbohydrates. This leads to a drop in rumen pH as sugars are fermented very rapidly and extensively to short-chain fatty acids. A low pH is suboptimal and digestion of other nutrients is slowed. This leads to a decrease in milk fat. To neutralize the pH in the rumen and prevent milk fat drop, buffers are added to the feed. The most commonly used buffer is sodium bicarbonate. It is effective in neutralizing rumen acids, but its effect is not long lasting. Magnesium oxide is a more powerful buffer and is usually added in combination with sodium bicarbonate for better effect. Seaweed, produced on the shores of the Irish Sea, is also an alternative. They have a stronger effect on pH than sodium bicarbonate and their effect lasts longer. pHiX-up is a strong buffer that is 3× stronger than sodium bicarbonate, but its effect is short-lived. Other buffers that can be used are also clays or yeasts, which also increase the low pH in the rumen.
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