Presence of dihydrostreptomycin and penicillin in cows' milk following intrauterine administration.

Cows were given liquid intrauterine infusions of dihydrostreptomycin and penicillin or dihydrostreptomycin alone approximately 24 hours after the onset of oestrus to determine the necessary withholding period for milk intended for human consumption. When dihydrostreptomycin and procaine penicillin were administered together, a withholding period of 72 hours provided an adequate safety margin. Thirty-six hours was an adequate withholding period when dihydrostreptomycin was administered.