Effect of Calcium and Starch Additions upon Ration Digestibility by Steers

Abstract

Two metabolism studies utilizing 40 steers were conducted to study the effect of added CaCO₃, starch and CaCO₃ plus starch upon digestibility and rumen fermentation when a 30% roughage ration was fed. Crude protein digestibility was not significantly different among treatments. Starch and CaCO₃ additions increased organic matter, energy and cellulose digestibilities. Nitrogen retention by the steers was increased by addition of starch to the basal ration. Rumen lactate concentration was increased by corn starch addition. Rumen protozoa concentration was significantly increased by starch addition; however, CaCO₃ addition decreased protozoa concentration. CaCO₃ addition increased molar concentration of rumen acetate and decreased molar concentration of propionate. Starch addition decreased rumen acetate concentration and increased rumen propionate. Rumen butyrate concentration was lowered by supplemental starch. Calcium or phosphorus retention was not significantly affected by treatments. Copyright © 1972. American Society of Animal Science . Copyright 1972 by American Society of Animal Science