Adaptation to High Concentrate Feeding as Related to Acidosis and Digestive Disturbances in Dairy Heifers

Abstract

When ruminants are changed from a primarily forage diet to one of increasing rates of daily concentrate intake, a point is reached when acute indigestion or off feed occurs. This condition is most dramatic when animals are fed ground wheat and at the time of off feed there is an accumulation of lactic acid in the rumen and a drop in rumen pH. When a concentrate mixture is fed, the change in lactic acid concentration and rumen pH is less marked. However, a daily increment of somewhat less than 7.0g concentrate per unit of metabolic body size, in combination with a feeding frequency of at least two times per day, was necessary to avoid off feed in yearling dairy heifers. An adaptation period of at least three weeks was necessary for heifers used in this study. High rumen acidity does not appear to be the only cause for an animal to go off feed, since buffers administered either by intraruminal infusion or feeding did not prevent off feed. Off feed must be caused by other factors acting separately or in combination with high ruminal acidity.