乾乳期における牛乳房炎の予防ならびに治療に関する研究

Abstract

A mastitis control program was carried out on cows in the dry period by intramammary infusion with an antibiotic preparation containing 500 mg of cloxacillin as benzathinesalt. Therapeutic and prophylactic effects of the preparation were examined bacteriologi-cally by changes in incidence of udder infection be-tween drying-off and calving.In the treated group, 91.9% of the udders infected at drying-off was eliminated and 95.9% of the healthy udders remaind normal at calving. Natural clear-ances were observed in 49.0% of the udders of the con-trol group, but the total udder infection rate increased to 47.5% at calving (41.5% at drying-off), as compared with 8.9% in the treated group (46.7% at drying-off).Clinical mastitis in the succeeding lactation period decreased in occurrence in the treated group.Udders infected with Sta phylococcus aureus at drying-off were all eliminated. More than 90% of Strepto-coccal infection also disappeared after intramammary infusion with 0.5g of Benzathine cloxacillin. The drug showed the same effect against Corynebacterium bovis, but was less effective against Sta. epidermidis in the treated group.After the clearance of the Staphylococcal infection, the milk production was soon raised to a normal level, but was delayed by the pre-existing Streptococcal in-fection.The therapeutic and prophylactic effects of clox-acillin on mastitis were demonstrated in 34 of 60 cowstreated in the dry period.