Effect of Corn Starch on Digestibility of Alfalfa Hay

Digestibility studies have been conducted on dairy cattle to investigate the effect of a readily digestible carbohydrate on the digestibility of alfalfa hay. Digestion trials of five or six days’ duration were carried out by the total collection method. When a 20-day preliminary period was allowed, the added carbohydrate had little, if any, effect on alfalfa digestibility. When no time was granted for adjustment to the starch addition, a highly significant depression of NFE, and significant decreases in protein and dry matter digestibilities, were observed. Evidence of other workers having a bearing on the relationship between preliminary periods and digestibility results has been presented. It is recommended that preliminary periods in digestibility trials with cattle consist of nine days as a minimum.