ALKALINE PHOSPHATASE ACTIVITY ASSOCIATED WITH THE WALLS OF DIFFERENT ORGANS OF THE GASTROINTESTINAL TRACT IN NEWBORN, YOUNG AND YEARLING BOVINES: EFFECTS OF DIET AND FASTING

Abstract

Alkaline phosphatase (APase) activity was assayed in tissue samples from the gastrointestinal tract (GIT) of newborn Holstein calves, and of 3- to 10-mo-old calves fed on milk only or starter-grower ration plus alfalfa hay. Statistical analysis of APase activity from different regions of the GIT showed effects of diet and site (P < 0.01) and an interaction of diet × site (P < 0.01) on APase activity. APase was high in the reticulo-rumen: intermediate in the omasum and the intestinal region: and low in the tongue, esophagus and abomasum. Within the same organ. APase differed considerably according to the location of the sites. Calves fed the fiber-containing diet had higher APase than those fed milk only. APase activity in the reticulo-rumen was much lower in newborn calves than in older calves, but in the other regions of the GIT, values were similar for the two groups. The effect of fasting on APase activity in rumen and abomasum walls of 20 yearling Hereford and Angus bulls fed on two different diets was also studied. In most cases, fasting decreased wall-associated APase activities. Interactions for breed × diet × site (P < 0.01), for breed × fasting × site (P < 0.01), and for diet × fasting × site (P < 0.05) on rumen APase activity, and for breed × diet × fasting (P < 0.01) on abomasum APase activity, were detected in this experiment. These variations in APase activity within the digestive tract are discussed in relation to the absorption capacity, degree of abrasion, and degree of keratinization of the tissues involved.