A total. of twenty breed cows with clinical signl of respiratory diseuse and mastitis from different farms in Alexandria city were involved fn this study. Oxytetracydin Hydrochloride
(0TC] pfizer Egypt) tryeceted intramuscular as a therapeutic dose 0f 20 mg/kg body welght for three successive days. Milk samples were collected immedk!te!y before flrst drug adminisration and then other 24,48, 72,96,120, 144, 168, 216. 264, 312,360. 408 and 456hr).
All milk samples showed positive results for presence of [OTC) 24hr. aFter first dose With concenttation value 3.05 ±o.88 mg/ml of mIlk and the concentration Increascd at 48.72,96hr then the level lowered 120 to 408hr. till not detected at 456hr.