Feed additives are typically not fed free choice because force-feeding ensures consumption of a needed nutrient. The exception has sometimes been salt, sodium bicarbonate, and sodium bentonite. We know animals have an appetite for salt and will self regulate. Many free choice minerals are salt based in an attempt to regulate the intake of minerals and vitamins in the mix. Also sodium bicarbonate has been offered free choice because of the belief that cows will consume extra during periods of acidosis when they need it. Another practice is to offer sodium bentonite free choice. Many dairymen have cows that eat soil and sodium bentonite may be a substitute because it is a clay like product. It is unknown exactly what sodium bentonite might do. We conducted a study to monitor free choice consumption of sodium bicarbonate and bentonite when offered side by side to groups of Holsteins and Jerseys. Sodium bicarbonate was force fed with other feeds to half the cows in each group. Jerseys consumed over twice the amount of bicarbonate than Holsteins but only slightly more bentonite. Also Jerseys did have elevated urinary pH's when offered free choice bicarbonate and bentonite. Both Holsteins and Jerseys preferred the bentonite to the bicarbonate. Because cows were group fed the free choice bicarbonate and bentonite we could not determine if those force fed bicarbonate consumed less than those not force fed, but we have no indication to believe they did. One field recommendation is cows should not consume more than .1 lb. of free choice sodium bicarbonate per day. If more is consumed this might indicate a problem with the ration. More interpretation is needed to allow more specific recommendations.

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