Comparison between Limestones and Cement Kiln Dusts of Similar Rates of Reactivity used in High Concentrate Diets for Beef Steers

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Abstract
A comparison was made of the influences of feed grade limestones and cement kiln dusts of similar rates of reactivity on nutrient utilization, feedlot performance, carcass merit and gastrointestinal tract characteristics of beef steers fed complete diets consisting of 15% corn silage and 85% concentrate. Diets were formulated to contain either materials with a fast rate of reactivity, limestone B and kiln dust D, or materials with a slow rate of reactivity, limestone A and kiln dust C. Average daily gains (kilograms) and dry matter intakes (kilograms per day) for the 140-day feeding trial were: (A) 1.04, 9.3; (B) 1.34, 9.5; (C) .91, 8.9, and (D) 1.41, 9.6. Steers fed diets containing either limestone B or kiln dust D had higher average daily gains and better feed efficiencies than steers fed diets containing either limestone A or kiln dust C. Rumen-cannulated steers fed diets containing either limestone B or kiln dust D had the least weight, volume, dry matter content and water content of reticuloruminal ingesta and had the highest reticuloruminal dry matter disappearance rate. Diets containing either limestone B or kiln dust D had the highest digestibilities of dry matter, organic matter, crude protein, cell walls and starch. Data indicate that feed grade limestones and kiln dusts of similar rates of reactivity produced comparable performance and physiological responses in ruminants. Furthermore, the beneficial results from the addition of certain kiln dusts to ruminant diets appear to have been associated with the form of calcium carbonate found in these kiln dusts, which had a fast rate of reactivity at pH values common in the forestomach and lower gastrointestinal tract of ruminants fed high concentrate diets. Copyright © 1981. American Society of Animal Science . Copyright 1981 by American Society of Animal Science.