The incidence and sources of penicillin in milk supplied to the city of Johannesburg.

The incidence of penicillin in bulk milk supplies to the city has varied from 1,2% to 2,6% over the past five years, and 3,2% of 366 pasteurised milk samples examined in 1975 were found to contain penicillin. Investigation of the sources revealed numerous instances of producers, milkers and veterinarians who had not acted responsibly in regard to the marketing of milk from treated cows. Details are provided. The legal and professional obligations of the veterinarian are emphasized. Reference is made to the dye marking registered intramammary formulations for farmer treatment of mastitis.