title: Evaluation of AOAC microbial diffusion procedure for analysis of chlortetracycline in high mineral feeds.
abstract: The performance of the AOAC microbial diffusion assay procedure for the analysis of chlortetracycline was evaluated in mixed feeds and premixes as well as laboratory-prepared feeds, all with various mineral contents. In 100 mixed feeds with a calcium content ranging from less than 1 to greater than 22%, no relationship was shown between calcium content and incidence of chlortetracycline deficiency. In 106 premixes, a relationship was shown between chlortetracycline content and adherence to guarantee: below 10 g/lb, the incidence of deficiency was high; in premixes containing 20 g chlortetracycline and above, the incidences of deficiency were less than 5%. In laboratory-prepared feeds containing 12-15% calcium, grinding and storage at both 4 degrees C and at room temperature (20 degrees C) caused no decrease in the chlortetracycline concentration. Only storage of the ground feed at 37 degrees C caused a distinct loss of activity. The temperature-related loss was attributed to the epimerization of chlortetracycline.
authors.affiliation: Rutgers University, Cook College, New Brunswick, NJ.
authors.forename: S E
authors.initials: SE
authors.lastname: Katz
authors.forename: H S
authors.initials: HS
authors.lastname: Ragheb
authors.forename: L B
authors.initials: LB
authors.lastname: Black
mesh_terms: D000821:Animal Feed / Q000032:analysis*; D002751:Chlortetracycline / Q000032:analysis*; D004058:Diffusion; D004355:Drug Stability; D008828:Microbiological Techniques; D008903:Minerals / Q000032:analysis*; D010406:Penicillins / Q000032:analysis; D013050:Spectrometry, Fluorescence; D013449:Sulfonamides / Q000032:analysis; D013696:Temperature
chemical_list: D008903:Minerals; D010406:Penicillins; D013449:Sulfonamides; D002751:Chlortetracycline