FLOW AND SOLUBLE PROPORTIONS OF ZINC, MANGANESE, COPPER AND IRON IN THE GASTROINTESTINAL TRACT OF SHEEP FED CORN OR ALFALFA SILAGES

Abstract

A set of four sheep, each fitted with a rumen cannula and a re-entrant cannula in the ascending duodenum and terminal ileum, were used for collection of rumen, duodenal and ileal digesta. A second set of four normal sheep was used for collection of feces and urine. The sheep were fed corn silage, urea-added corn silage, formic acid-treated alfalfa silage or wilted alfalfa silage in latin square design. Soluble proportions of manganese in rumen fluid, ileal digesta and feces were much lower on alfalfa silages than on corn silages although the soluble proportions in the duodenal digesta were not different. The soluble proportions of zinc, copper and iron were not as consistent as those of manganese. The apparent absorption of zinc was negative on alfalfa silages, and was associated with the lower soluble proportion of zinc in duodenal digesta and higher in the ileal digesta, as compared to corn silages. The apparent absorption of iron was much higher on corn silages than on alfalfa silages. Addition of urea to corn at ensiling resulted in an improvement of apparent absorption of copper. Key words: Trace elements, solubility, absorption, corn silage, alfalfa silage, sheep