The Influence of Corn Starch upon Roughage Digestion in Cattle

Abstract

Five series of digestion trials with cattle (steers) were carried out to obtain more information on the effect of starch upon roughage digestion. In the first trial, a basal ration containing corncobs and dried skimmilk was fed at a constant level to which varying amounts of mineralized corn starch was added. In the second, third, and fourth series the basal feed consisted of high quality alfalfa hay to which were added different amounts of starch. The final series included starch additions to a constant mixture of corncobs and limited alfalfa hay. A substantial decrease in roughage dry matter digestion was noted when starch was included in the ration in which corncobs or corncobs and limited alfalfa hay made up the roughage part of the ration. This decrease in roughage digestion occurred even though the percent protein in the total ration was widely different. Minor decreases in roughage digestibility were noted in two alfalfa series and no decrease in a third alfalfa series. The variable influence of starch upon roughage digestion can best be explained on the basis of adequate or inadequate nutrients for the growth of microorganisms in the alimentary tract, associated either with starch fermentation or roughage digestion.