EFFECT OF DIETARY PROTEIN ON THE SOLUBILITIES OF MANGANESE, COPPER, ZINC AND IRON IN THE RUMEN AND ABOMASUM OF SHEEP

Abstract

Four sheep, each prepared with a rumen fistula and re-entrant cannula in the proximal duodenum, were fed hourly diets containing 7, 11, 15 and 19% crude protein in a 4 × 4 latin square experiment. Solubilities of manganese, copper, zinc and iron were much lower in the rumen than in aqueous extracts of the diets but those of manganese and zinc dramatically increased on passage through the abomasum. There was no effect of dietary protein on the solubility of manganese, zinc and iron in the rumen and abomasal digesta flowing into the duodenum. The solubility of copper was proportionally decreased in both rumen and abomasal digesta with the increasing dietary protein. It is concluded that the dietary concentration of protein is one of the important factors affecting the solubility of copper in the stomach of ruminants.