Trace element release in response to contact electrolysis of bimetallic slugs in a simulated rumen environment

Abstract

TRACE ELEMENT RELEASE IN RESPONSE TO CONTACT ELECTROLYSIS OF BIMETALLIC SLUGS IN A SIMULATED RUMEN ENVIRONMENT A.C. BRAY Dept of Agricultural Science, University of Tasmania, GPO Box 252C, Hobart, Tas. 7001 The period over which gastro-intestinal slow release mineral devices release nutritionally significant amounts of mineral may be limited either by a failure in the retention of the device or by a number of factors that inhibit the release of the mineral in question. For example, MacPherson (1984) reported that the dosing of copper deficient cows with copper oxide needles maintained normal blood copper levels at the most for 396 days. As far as the author is aware contact electrolysis has not been used as a technique to release minerals from metals placed in the gastro-intestinal tract. Contact electrolysis occurs when a metal is corroded through aqueous contact with another metal of higher electromotive force. The rate of corrosion is a function of both the salt content of the environment and the distance between the 2 metals in terms of electromotive force. The rumen would seem to have the attributes (aqueous with a variety of salts in solution) to facilitate this process. The experiments reported here are concerned with the electrolysis of copper from copper metal in contact with nickel or nickel alloys (Into Nickel Alloys, Wright and Co Ltd, Sydney, Australia) in one trial using a simulated rumen environment (Rusitec of Czerkawski and Breckenridge 1977). Nylon gauze bags each initially containing 8 g of lucerne chaff (10 ppm Cu) were added to each Rusitec vat on alternate days and were then replaced with similar bags after 48 hours fermentation; artificial saliva flow was 750 mL/day.vat. Three bimetallic slugs and a copper slug (copper components were approximately 12 g) with overall slug measurements of 12 mm diameter by 25-30 mm long consisting of (a) coppernickel 200 (99.5% Ni), (b) copper-Inconel 601 (60.5% Ni, 14.1% Fe, 23% Cr), (c) copper/Incoloy SO0 (32.5% Ni, 46% Fe, - 1% Cr) and (d) copper were distributed between the 4 vats. Copper was determined 3 by atomic absorbtion spectroscopy on acid digests of vat fluid. Vat fluid copper concentrations (average of 5 samples taken over 10 days) are presented in Table 1. Table 1. The concentration (2 s.e.m.) of copper &g/L) in Rusitec vat fluid prior to and after the addition of metallic slugs These preliminary results indicate that Rusitec system to a variable extent . In investigate the effects of varying the weight release of other metals from anodes such as is also planned to test the release of copper contact electrolysis of copper metal did occur within the view of these results further in vitro trials are planned to ratios and surface area relationships of the 2 metals and the zinc and various alloys. A copper repletion study with sheep from the bi-metallic slugs irz Go. MACPHERSON, A (19S4). III 'Trace Element Metabolism in Man and Animals-j',( Eds C.F.Mills. I. Bremner and J.K. Chesters) pp. 733-5 (Commonwealth Agricultural Bureaux: Slough). CZERKAWSKI, J.W. and BRECKENRIDGE, G. (1977). Br-. J. Nut]-. 38: 371-84. 440