PREPARTUM ANTIBIOTIC-THERAPY WITH A CEPHAPIRIN DRY-COW PRODUCT AGAINST NATURALLY-OCCURRING INTRAMAMMARY INFECTIONS IN HEIFERS

Intramammary infusion of a dry-cow antibiotic preparation containing 3 00 mg of cephapirin benzathine into 18 Jersey heifers, 10-12 weeks pre partum, resulted in cure rates of existing intrammary infection (IMI) of 96% (24/25), 100% (4/4), and 90% (28/31) for Staphylococcus aureus, Streptococcus species, and Staphylococcus species, respectively. Cure rates of IMI that had been treated with a lactating-cow therapy conta ining 200 mg cephapirin benzathine at parturition were 62.5% (15/24), 100% (22/22), and 100% (3/3) for Staphylococcus aureus, Streptococcus species, and Staphylococcus species, respectively. Initial somatic cel l counts (SCC) of secretions from infected quarters were greater than from uninfected quarters. At 2 months postpartum, the SCC of milk from treated and cured quarters were reduced in comparison with quarters t hat remained infected. Cephapirin benzathine was present at detectable concentrations in 94, 80, 68, and 61% of treated quarters at 1, 2, 3, and 4 weeks after infusion of the cephapirin dry-cow product, respect ively. At parturition, 24% of treated quarters were positive for antib iotic, however, no quarters remained positive for antibiotic at 5 days postpartum. An additional 40 heifers from a commercial herd were samp led and infused in all quarters with the cephapirin dry-cow product at 16-20 weeks prepartum. Cure rates for the commercial herd were 94% (2 9/31), 94% (16/17), 100% (44/44), and 100% (3/3), respectively, for qu arters infected by S. aureus, Streptococcus species, Staphylococcus sp ecies, and coliforms.