Sulfur Requirement of Lactating Dairy Cows. II. Utilization of Sulfates, Molasses, and Lignin-Sulfonate

Two experiments were designed to evaluate sodium and calcium sulfate, cane molasses, and lignin-sulfonate as sources of dietary sulfur for lactating dairy cows. Dietary sulfur was .15 and .30%. Molasses was fed at 14% of the ration dry matter, and sodium sulfate was added to attain .15 and .30% sulfur in the complete diet. Calcium sulfate was supplied in agricultural gypsum. Corn silage supplied 507o of the dry matter in each ration. In a third experiment comparisons were among diets containing .06, .10, .18, .26, ,31, and .42% sulfur supplied in the basal ration by added increments of sodium sulfate, potassium and magnesium sulfate, and agricultural gypsum. Milk production and positive sulfur balances were comparable with the various sulfate sources of sulfur between .15 and .26% sulfur in the diet. From 65 to 77% of the sulfur in molasses was available for absorption in cows which was slightly less than the availability of sulfur from sodium sulfate (77 to 87%). Sulfur from lignin-sulfonate was poorly digested (42 to 53g). Calcium sulfate sulfur from agricultural gypsum was absorbed as well as sulfur from sodium sulfate and a mixture of magnesium and potassium sulfate and allowed normal feed intake up to 450 g per day (.15% sulfur in the complete diet on a sulfur basis). When agricultural gypsum was used to increase dietary sulfur to .30% or more, feed intake decreased. Excessive retention of sulfate sulfur appeared also at dietary sulfur above .30~ with all sources of sulfate.