Absorption of 45Ca and 89Sr from the abomasum of the calf.

Abstract

In vivo experiments, using 12 anesthetized calves, were conducted to determine the extent of abomasal absorption of 45Ca and 89Sr. In two experiments, one with milk-fed calves and another with hay and grain-fed calves, a large amount of variation in absorption was noted. This was attributed to a lack of mixing of the isotope with abomasal ingesta. Variability was reduced in a third experiment by increasing the dose volume to 225 ml. An average of 20.8 ± 3.1% of an administered dose of 45Ca and 3.2 ± 3.0% of 89Sr were absorbed from the abomasum within 25 min. These estimates were based on the amounts of isotope recovered from ingesta and abomasal tissue of four animals and is substantiated by the rapid appearance of 45Ca in venous blood drained from the abomasum.