The use of an internal teat sealant (ITS) at dry-off has been repeatedly shown to improve udder health in the subsequent lactation. However, almost all ITS research conducted in North America has evaluated one product (Orbeseal, Zoetis, Parsippany, NJ). The objective of this study was to evaluate a new ITS product (Lockout, Boehringer-Ingelheim Animal Health, Duluth, GA), by comparing it directly to Orbeseal in a multi-site, randomized, positively controlled equivalence trial for health indicators during the dry period [quarter-level new intramammary infection (IMI) risk, IMI cure risk, and IMI risk at 1 to 13 d in milk, DIM] and during the first 100 DIM [clinical mastitis and culling or death risk and test-day milk somatic cell count (SCC) and milk yield]. At dry-off, cows were randomly allocated to be treated with Orbeseal or Lockout after blanket administration of a cloxacillin dry cow therapy product. Cows were then followed from dry-off until 100 DIM. Intramammary infection status at enrollment and at 1 to 13 DIM was determined using standard bacteriological methods, allowing for the measurement of IMI dynamics during the dry period (i.e., IMI cures and new IMI). The effect of ITS group on dry period IMI cure, dry period new IMI, and IMI risk at 1 to 13 DIM was determined using generalized linear mixed models (logistic). Marginal standardization was used to derive risk difference estimates. An equivalence hypothesis test was conducted to compare ITS groups for dry period new IMI risk (margin of equivalence was ±5% units). The effect of ITS group on clinical mastitis and culling or death was determined using Cox proportional hazards regression. The effect of ITS group on test-day SCC and milk yield was determined using linear mixed models. Final models indicated that measures of quarter-level IMI dynamics were similar between ITS groups (i.e., risk difference estimates and 95% confidence intervals all close to zero). Furthermore, Lockout was found to be equivalent to Orbeseal for dry period new IMI risk using an equivalence hypothesis test. Hazard ratio estimates for clinical mastitis and culling or death were close to 1 and differences in SCC and milk yield between ITS groups were close to 0, indicating negligible effects of ITS group on test-day SCC and milk yield. In most cases, these effect estimates were relatively precise (i.e., narrow 95% confidence intervals). We conclude that producers using blanket dry cow therapy could consider including Orbeseal or Lockout treatment in their programs.
Bibliographical noteFunding Information:
The study investigators have no financial interest to declare. Funding for this study was provided by Boehringer-Ingelheim Animal Health (Duluth, GA). We are very grateful for the participation and tremendous cooperation by owners and staff at the 5 participating dairies. We also thank the technicians that assisted at each study site: California (Maria Amaral, Gema Camacho, Pablo Duque, Pallavi Nahata, Kruthika Patel, Maria Jose Perez, Cinthya Tovar, and Juanita Zaragoza; Dairy Experts, Tulare, CA) and Minnesota (Kelli Bowman, Joshua Brown, Pedro Paulo Cecillio Ferro, Chandra Dahike, Kaylan Risacher, and Victor Moro Taveira; University of Minnesota, St. Paul), as well as Francisco Leal Yepes (Cornell University, Ithaca, NY) who conducted fieldwork in New York. Author roles are as follows: S. M. Rowe was involved in local and multi-site coordination, fieldwork, laboratory work, data management, statistical analysis and manuscript preparation. S. M. Godden was involved in study conceptualization, herd recruitment in Minnesota, supervision of fieldwork and manuscript editing. A. Lago was involved in study conceptualization, local site coordination, fieldwork and manuscript editing. D. V. Nydam was involved in study conceptualization, herd recruitment in New York, fieldwork, and manuscript editing. E. Royster was involved in study conceptualization and manuscript editing. A. K. Vasquez was involved in fieldwork, local site coordination and manuscript editing. J. Timmerman was involved in laboratory work and manuscript editing. The authors have not stated any conflicts of interest.
© 2020 American Dairy Science Association
- dry cow therapy
- intramammary infection
- teat sealant