Effects of 2 intramammary antimicrobial formulations on control of mastitis during the dry-period and performance of dairy cows

ABSTRACT Objectives Our objective was to evaluate the effects of benzathine cloxacillin (BC) and ceftiofur hydrochloride (CH) treatment at dry-off on prevalence of intramammary infections at calving, incidence of clinical mastitis and SCC and milk yield up to 100 DIM, and removal from the herd and reproductive responses within 100 DIM. Materials and Methods At dry-off, cows from 2 herds were assigned randomly to the BC (n = 1,160; Orbenin-DC, Merck Animal Health) and the CH (n = 1,183; Spectramast DC, Zoetis) treatments. Composite milk samples collected at dry-off and at calving were submitted for bacterial culture. Monthly milk samples were used to determine SCC. Days in milk at first insemination and pregnancy outcomes to first and second inseminations were compared between the 2 treatments. Results and Discussion Treatments did not differ regarding prevalence of intramammary infections at dry-off (BC = 45.2 ± 1.8% vs. CH = 42.6 ± 1.7%). Treatment did not affect the prevalence of intramammary infections at calving (BC = 39.1 ± 2.3% vs. CH = 40.4 ± 2.3%), incidence of clinical mastitis within 100 DIM (BC = 6.6 ± 1.0% vs. CH = 7.7 ± 1.1%), and milk yield up to 100 DIM (BC = 3.6 ± 0.03 kg × 103 vs. CH = 3.6 ± 0.03 kg × 103). Treatment did not affect reproductive outcomes. Implications and Applications Producers may choose between BC and CH at dry-off without being concerned about differences in prevalence of IMI at calving and lactational performance.