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 300 mg of cephapirin benzathine into 18 Jersey heifers, 10-12 weeks prepartum, 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 containing 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 cell 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 that 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, respectively. At parturition, 24% of treated quarters were positive for antibiotic, however, no quarters remained positive for antibiotic at 5 days postpartum. An additional 40 heifers from a commercial herd were sampled and infused in all quarters with the cephapirin dry-cow product at 16-20 weeks prepartum. Cure rates for the commercial herd were 94% (29/31), 94% (16/17), 100% (44/44), and 100% (3/3), respectively, for quarters infected by S. aureus, Streptococcus species, Staphylococcus species, and coliforms.