|dc.description.abstract||Biosecurity practices of beef cow-calf herds in western Canada have not been studied extensively, and the impacts these practices have on animal health with the herd. The association between not implementing good biosecurity practices and herd health in cow-calf herds is not well understood. This study used a survey of 103 cow-calf producers who were part of the Western Canadian Cow-Calf Surveillance Network. Eighty-one questionnaires were returned. The questionnaire asked about current cattle inventory, other animals on the farm (dairy cattle and other species), purchased animals, source of purchased cattle, procedures done to purchased cattle (i.e. disease testing and vaccinations), commingling with other herds, management of people and equipment, and biosecurity within the herd. There were also questions about the incidence of diseases within the herd to determine the impact of biosecurity practices on animal health. During the study period of 2014-2017, all the herds purchased bulls, 54% of herds purchased heifers, and 42% purchased cows. The use of standard biosecurity practices was generally low with 30% of producers keeping purchased animals separate and 30% vaccinating new additions. Logistic regression models found that none of the biosecurity practices were significantly associated with having Johne’s disease. The purchase of 10 bulls or more over the four years, and the purchase of any cows from other farms or private sales was associated with a higher risk of reporting an outbreak of Bovine Respiratory Disease (BRD) in the herd. Not vaccinating animals purchased into the herd and use of community pasture also was associated with the risk of a BRD outbreak. Outbreaks of calf diarrhea were similarly significantly associated with the purchase of over 10 bulls and use of community pasture, as well as leasing and sharing bulls. Biosecurity is not emphasized on cow-calf farms in western Canada and the purchase of adult cattle and using community pasture are risk factors for BRD and calf diarrhea.
Next, was a study to describe the prevalence and antimicrobial sensitivity of 3 major BRD bacterial pathogens from auction market derived vs single ranch source calves, at arrival and later in the feeding period. The animals enrolled were 299 calves of various beef-type breeds derived from multiple auction markets (AUCT) and 300 similar breed-type-calves sourced directly from a single ranch (RANCH). All calves were sampled using a deep nasal pharyngeal swab at the time of entry to the feedlot and again at 64 to 168 days after arrival. The swabs were cultured within 24 hours of sampling and sensitivity testing of isolates for Mannheimia haemolytica (MH), Pasteurella multocida (PM) and Histophilus somni (HS) was performed. In the AUCT calves, the prevalence of MH decreased significantly from 38% to 20% (P <0.001), and the prevalence of HS increased significantly from 17% to 30% (P = 0.001) between sampling events. In the AUCT calves there was an increase in calves with MH isolates not sensitive to tulathromycin from 1% in the first sample to 7% in the second. There was also a significant increase in calves with PM isolates not sensitive to florfenicol (from 0% to 3%), oxytetracycline (from 1% to 4%) and tulathromycin (from 0% to 3%). Finally, in the AUCT calves there was a significant increase in calves with HS isolates not sensitive to oxytetracycline (from 0% to 12%), tilmicosin (from 0% to 10%) and tulathromycin (from 0% to 9%). In the RANCH calves, prevalence of all pathogens decreased significantly throughout the study. From 30% to 20% (P = 0.01) for MH, from 60% to 43% (P <0.001) for PM and from 40% to 6% (P <0.001) for HS. In the RANCH calves there was a significant decrease in calves with MH isolates that were not sensitive to oxytetracycline (from 6% to 0%), tilmicosin (from 5% to 0%), and tulathromycin (from 5% to 0%). There was also a significant increase in calves with PM isolates not sensitive to florfenicol (from 0% to 9%), oxytetracycline (from 0% to 10%), tilmicosin (from 2% to 14%) and tulathromycin (from 0% to 10%). There were few or no isolates not sensitive to ceftiofur or enrofloxacin. Antimicrobial resistance of BRD pathogens and prevalence of bacterial pathogens can vary over the feeding period differently in calves sourced either from auction markets and directly from a single source.||