Stability of bacitracin methylene disalicylate and chlortetracyline in combination in a pelleted pig feed

A study was carried out to determine if the presence of bacitracin methylen e disalicylate (BMD) interfered with the assay of chlortetracycline (CTC) a nd if the presence of CTC interfered with the assay of BMD when both are co mbined in a pig feed. In addition, the potential influence of steam pelleti ng on active concentrations of BMD and CTC was determined. Further, the sta bility of BMD in the presence of CTC and the stability of CTC in the presen ce of BMD was determined in pelleted pig feed. Finally, the homogeneity of BMD and CTC during normal mixing procedures and the extent of segregation d uring shipping were determined. The results of the study demonstrated that when present in pig feeds at levels anticipated for actual use, BMD and CTC can be assayed without interference, that each of these antibiotics remain s within specifications for up to 13 weeks of storage and that standard fee d mixing results in homogenous dispersion of the antibiotics which remain d ispersed following transport. (C) 1999 Elsevier Science B.V. All rights res erved.