Limestone Buffers in Complete Mixed Rations for Dairy Cattle

Abstract

In two feeding trials lactating dairy cows were fed limestone and in one trial growing dairy heifers were fed magnesium-limestone-buffered rations. Complete mixed rations based on corn silage and corn grain were fed ad libitum. In Trial 1, cows fed a ration with 2.76% limestone consumed 7.36% less dry matter of feed than cows fed a ration containing .11% added limestone, with no effect on milk production. In Trial II, cows fed a ration with 2.71% limestone had similar feed intakes and milk production but gained more weight than cows fed a ration with .01% limestone. Heifers fed a ration supplemented with magnesium limestone gained .49 kg more weight per day and made more efficient use of feed than heifers fed the nonsupplemented ration. Limestone increased fecal pH from 5.99 to 6.62 in Trial 1, 6.13 to 6.57 in Trial II and decreased loss of starch in feces. Magnesium limestone increased fecal pH from 6.37 to 6.76 and decreased starch in feces from 5.60 to 1.14%. In these trials both limestone and magnesium limestone increased fecal pH, reduced starch losses in the feces, and improved feed efficiency. © 1976, American Dairy Science Association. All rights reserved.