When feeding a herd of lactating cows, the fermentation in the rumen will produce organic acids: acetic, propionic, and lactic. Higher fiber diets tend to produce relatively more acetic acid and less propionic acid. High grain diets will produce more acid, and produce relatively more propionic acid than acetic acid. Cows use all the acids as energy sources, but they specifically use acetic acid to make milk fat, and propionic acid to make milk sugar-lactose.
Raising the levels of grain feeding increases energy intake, and usually milk production. When carried too far, this substitution of grain for higher fiber forages reduces the fat content of milk and causes an acidosis condition in the rumen. The ration consisting of heavy grain feeding and all-corn silage forage, especially finely chopped low-fiber silage, also appears to create an acidosis condition in the cow. As expected, a reduced intake of feed occurs, cows may occasionally go off-feed, and a depressed milk fat percent results.
Feeding 12 to 15 lbs. of long stem hay daily per cow will usually overcome this condition. The hay apparently stimulates more cud-chewing and swallowing of large quantities of saliva, which serve as a buffer to create a more alkaline condition in the rumen.
If it is not practical to increase hay feeding, sodium bicarbonate (baking soda) can serve as a buffering agent to correct the acid condition in the rumen. A combination of 0.4 lb. of sodium bicarbonate and 0.2 lb. of magnesium oxide fed daily per cow appears to be better than either one fed separately.
An alternative to buffers is feeding additional soluble fiber, 12-18 lbs of high relative feed value hay, or concentrates such as Turbo Plus WCS.
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