Trace element nutrition of grazing ruminants. 1. Degree of oxidation, diet, frequency of dosing and location in the gastro-intestinal tract as factors affecting the ability of oxidized copper wire to promote hepatic copper storage
1986
Langlands, J.P. | Bowles, J.E. | Donald, G.E. | Smith, A.J. (Commonwealth Scientific and Industrial Research Organization, Armidale (Australia). Div. of Animal Production)
Incorporation of Mo and S into the diet did not reduce hepatic Cu storage, but storage was negligible when elemental Cu was used; dose rates might be manipulated by varying the extent of oxidation of the particles. Oxidized particles were relatively ineffective when held in the rumen in a nylon bag, and some of the variability in the pattern of hepatic Cu storage after dosing is likely to be associated with the rate of clearance of the particles from the rumen; there was no evidence of ineffectiveness after retention in the rumen for 6 weeks. Excessive hepatic Cu concentrations, observed in some sheep, were attributed to the quantity of supplement given, the high Cu content of the basal diets, and failure to scale the dose in proportion to liver weight or live weight. Dosing at 6-monthly intervals reduced variability in hepatic Cu concentration through time, but the strategy may lead to unacceptable hepatic Cu concentrations unless dose rates or the extent of oxidation are reduced.
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