Persistence of Tartrazine in Marking Sheep Wool

Tartrazine was examined as a possible replacement marker for rhodamine B in the Livestock Protection Collar. Test solutions were formulated in six combinations; tartrazine at 0.5% and 1.07. concentrations, with and without compound 1080, and with and without nigrosin black. Each solution was examined for persistence of color in the laboratory and when applied to the wool of dried sheep hide. Hide pieces were allowed to weather naturally or were sprinkled to simulate rain. Tartrazine alone was also tested at concentrations of 0.5% and 1.0% on the necks of sheep. Over a 3—month period, no fading was noted in the laboratory for any test solution. When applied to wool, no loss of color was attributed to 1080 or nigrosin black and no long-term advantage was detected for a 1.0% over a 0.5% tartrazine solution, except on the sprinkled pieces. Tartrazine usually provided an identifiable mark on the wool of dried hides and on live sheep for 1 to 2+ months, depending on test conditions. Tartrazine is an acceptable replacement for rhodamine B in the Livestock Protection Collar. INTRODUCTION Compound 1080 (sodium monofluoroacetate) was registered by the U. S. Environmental Protection Agency (EPA) in July, 1985 (Registration #56228-22) for use in livestock protection collars (LPCs) to control coyote predation on sheep or goats (Moore 1985). The LPC consists of a 2Both authors are from the Denver Wildlife Research Center, Animal and Plant Health Inspection Service, U. S. Department of Agriculture, Denver, CO 80225-0266. compartment rubber bladder containing a solution of compound 1080 and rhodamine B. The collar is fitted around the necks of sheep or goats exposed to coyote predation. The characteristic throat attack by coyotes usually results in punctures of the LPC and delivery of a lethal dose of solution to the attacking coyote (Connolly and Burns Accepted). Rhodamine B was included in the solution as a dye to help identify punctured or leaking collars. Rhodamine B has been identified by EPA as requiring further study before being accepted as an inert ingredient in pesticide formulations (Moore 1987), and identification of a suitable alternative became desireable. Tartrazine (FD & C yellow #5), recognized as a safe, nontoxic dye frequently used in coloring foods (Gardner 1979), could replace rhodamine B in LPCs if it produced a suitable stain on wool. This study assessed the potential of tartrazine for marking sheep wool, and determined if the color was influenced by the compound 1080 used in LPCs. To be satisfactory, the dye should be identifiable on wool for a minimum of 1 week under the environmental conditions prevailing in the area of intended use. We thank G. E. Connolly, M. W. Fall, and F. F. Know1 ton for helpful comments on this paper. METHODS Tartrazine was dissolved in distilled water at two concentrations, 0.5% and 1.0%. Portions of each solution were then formulated into two more test solutions by adding Compound 1080 (10 mg/ml) and compound 1080 (10 mg/ml) with 0.5% nigrosin black (a dye added to Compound 1080 by the supplier to identify their technical product). About 10 ml of each of the 6 test solutions were placed in individual 15