Mode of transfer of antibiotics from treated to nontreated quarters in dairy cows
Ziv, G.; Gordin, S.; Bechar, G.
American Journal of Veterinary Research 35(5): 643-647
1974
ISSN/ISBN: 0002-9645 PMID: 4133826 Document Number: 77116
11 lactating Israeli-Friesian cows received injections into the right front quarter of 2 g ampicillin sodium (A), 1.8 g erythromycin estolate (E), 100 000 IU benzylpenicillin (B) containing 0.2 mCi B, 100 mg dihydrostreptomycin (D) containing 0.8 mCi D, or 100 mg tetracycline (T) containing 0.8 mCi T. After treatment with B, D or T no antibiotic activity was detected in blood serum or milk from untreated quarters. However, radioactive counts were recorded in serum and in milk from untreated quarters 1-8 h after antibiotic injection. Milk to blood serum ratio of radioactivity for untreated quarters was approx. 1 for T, >1 for D and <1 for B; milk to blood serum ratio for antibiotic activity in untreated quarters was >1 for E and <1 for A. Concn. of E in milk from untreated quarters was higher in more acidic milk whereas A concn. was higher in milk of pH 7.0 than 6.6. It is suggested that the major route of antibiotic transfer from treated to untreated quarters is via the blood.