EFFECTIVENESS OF AN INTERNAL TEAT SEALANT IN THE PREVENTION OF NEW INTRAMAMMARY INFECTIONS DURING THE DRY AND EARLY LACTATION PERIODS IN DAIRY Cows WHEN USED WITH AN INTRAMAMMARY ANTIBIOTIC

摘要

The primary objective of this study was to describe whether quarters treated with an internal teat sealant in addition to an antibiotic at dry off would develop fewer new intramammary infections during the dry period and early lactation, as compared to quarters treated with antibiotic alone (control). Secondary objectives were to describe the effect of treatment on the prevalence of intramammary infection after calving, the incidence of clinical mastitis events between dry off and 60 DIM, and LS after calving. 437 cows with four functional quarters and no evidence of clinical mastitis were enrolled on the day of dry off. On the day of dry off all four quarters were sampled for culture and SCC measures. After the final milking all four quarters wereroutinely infused with a commercially available long-acting antibiotic. Two contra-lateral quarters (LF/RH or RF/LH) were then randomly assigned the additional treatment of infusion with an inert internal teat sealant. The teat sealant was stripped out at first milking and the quarters re-sampled at both 1-3 DIM and 6-8 DIM for culture and SCC analysis. The incidence of new intramammary infections occurring between dry off and 1-3 DIM was 25.9% and 20.6 % for control vs. treated quarters, respectively.Quarters treated with an internal teat sealant and antibiotic at dry off, as compared to quarters treated solely with an antibiotic, were 27% less likely to acquire a new intramammary infection between dry off and 1-3 DIM. The prevalence of infection at1-3 DIM was 29.5% and 23.3%, for control vs. treated quarters, respectively. Quarters treated with an internal teat sealant and antibiotic at dry off, as compared to quarters treated solely with an antibiotic, were 30% less likely to have an intramammaryinfection present at 1-3 DIM. There was a significant reduction in SCC associated with treatment. The LS mean linear scores (and corresponding geometric mean SCC) for control vs. treated quarters were 5.45 (546,516 cells/ml) vs. 5.16 (446,605 cells/ml)at 1-3 DIM, and 3.23 (117,283 cells/ml) vs. 2.92 (94,606 cells/ml) at 6-8 DIM.