Evaluation of methanol extraction for determination of bacitracin in feeds

Five laboratories evaluated methanol extraction for the determination of zinc and methylene disalicylate (MD) bacitracn in swine and poultry feeds at 100 g/ton and 2 premixes labeled 50 g/lb (MD bacitracin) and 40 g/lb (zinc bacitracin). Bacitracin activity was determined on each of 2 days with 2 dilutions on each day. No significant difference was found between dilutions within a day or between days for each sample. The kind of bacitracin or type of feed did not significantly affect results.