Cobalt metabolism in sheep

Abstract

Experimental trials employing ruminants have presented data revealing that oral administration of antibiotics to these animals may result in severe digestive disturbances. There is good evidence, however, that calves can benefit from antibiotic administration at least until the rumen is functioning effectively.

The results of previous invstigation in this laboratory demonstrated the relative distribution of cobalt60 in various tissues and gastro-intestinal contents of the sheep. In addition, attempts were made to extract vitamin B12 from various isolated samples to enable the study of cobalt and vitamin B12 relationships. The vitamin B12 extraction procedure employed in this instance, however, has since proved unreliable.

Research reported in this thesis concerns the extension of this work with particular emphasis on the following: 1) precise partition of organically bound cobalt and inorganic cobalt; 2) the determination of the fraction of the total cobalt found in tissues and gastro-intestinal contents bound as vitamin B12 cobalt; 3) localization of vitamin B12 synthesis and absorption in the gastro-intestinal tract; and 4) the determination of correction factors to be applied to measured cobalt and vitamin B12 concentrations in the ingesta to compensate for the effect of absorption of macronutrients on these concentrations, this correction to be obtained by the use of chromic oxide as an index of digestibility.