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.

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ホルスタイン種雄子牛16頭を4頭ずつ4群に分け, 牛肺虫と小型ピロプラズマを混合感染した場合の影響を明らかにするため, 各々の単独感染および無感染対照とその比較を行なった結果は以下のとおりであった.
牛肺虫と小型ピロプラズマとの混合感染群で1頭が死亡し, 牛肺虫単独感染群に比べて牛肺虫子虫数の増加と, 排泄期間が延長する傾向が認められたが, 臨床症状では明らかな差を示さなかった.子牛の発育に及ぼす影響をみると, 牛肺虫単独感染と混合感染のものが, 小型ピロプラズマ単独感染のものより増体が悪かった.

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