Q. I have a lot of downed corn ears in my field. Can I feed sodium bicarbonate either free choice or put it in the water and turn cows out to graze?
A. Most of the work with sodium bicarbonate is adding it to the diet and evaluating how it works to prevent acidosis in grain adapted animals. These animals have a population of bacteria built up that can use lactic acid, which is produced by other bacteria in the rumen when digesting corn. Thus, the sodium bicarbonate will be neutralizing mostly other acids (such as propionate and acetate) that are not as strongly acidic as lactic acid. The improvement (increase) in ruminal pH, even in these situations is inconsistent. Feeding sodium bicarbonate does sometimes increase ruminal pH and other times, it has not. The amounts tested vary. Sometimes it appears to have an effect at 1 to 1.5% of the diet, but then has not worked at that level or even higher levels, like 5% of the diet. From these experiences, using sodium bicarbonate to control even subacute acidosis is unreliable at best.
Additionally, the issue with grazing cows on downed corn is that we are essentially feeding corn to un-adapted animals. In this case, the goal is to have the sodium bicarbonate neutralize a great deal of a very strong acid (lactic acid) that is being produced. Thus, providing even high amounts of sodium bicarbonate (or other buffers) and expecting it to maintain increased ruminal pH is unrealistic.
Lastly, in the situations where we feed sodium bicarbonate, either free choice or in the water, the intake will be inconsistent and not related to the amount of corn consumed. Also, when providing it in the water some animals will be deterred from drinking.
Therefore, I would not recommend depending on sodium bicarbonate in the water or providing free choice to prevent acidosis (grain overload) when cattle are grazing downed corn. Instead, the best management practice is to adapt the rumen bacteria to corn to increase the number of lactic acid using bacteria. See “Down Corn: Problem or Opportunity for Cattle Producers?” for information on how to adapt cattle.
Cattle that become acidotic for even a short time can have reduced performance long term due to damage to the rumen wall. Therefore, taking the time to avoid acidosis is very important.
Mary Drewnoski, UNL Beef Systems Specialist
University of Nebraska-Lincoln