AN EPIDEMIOLOGIC-STUDY OF SELECTED CALF PATHOGENS ON HOLSTEIN DAIRY FARMS IN SOUTHWESTERN ONTARIO

  • 1 July 1986
    • journal article
    • research article
    • Vol. 50  (3) , 307-313
Abstract
Fecal samples from calves on 78 randomly selected Holstein dairy farms in southwestern Ontario were screened for Salmonella, Campylobacter jejuni/coli, enteropathogenic Escherichia coli, rotavirus and coronavirus. Based on the observed prevalence, 22% of farms had calves infected with Salmonella, 13% with Campylobacter jejuni/coli, 41% with enteropathogenic E. coli, 19% with rotavirus and 5% with coronavirus. These estimates can be modified, using a method developed by Mullen and Prost (1983) for the World Health Organization, to account for the nature of the laboratory test used. It the test is assumed to have no false positives (that is, if an organism is detected must be there), then the observed prevalence estimates seen on this study may greatly underestimate the true prevalence of infected premises. The use of nipple feeders for calves was associated with an increased probability of farms having calves shedding detectable fecal levels of Salmonella, E. coli, or one of the two viruses. The use of group pens was associated with an increased odds of finding C. jejuni. Calves with diarrhea on these farms tended to have increased odds of shedding rotavirus, and E. coli with the K99 antigen. However, at the farm level, none of the organisms was associated with above median levels of morbidity. Farms positive for one or other of the viruses had increased odds of experiencing calf mortality relative to virus-negative farms, and farms positive for C. jejuni/coli had decreased odds of mortality. In a separate study utilizing calves form some of the survey farms, scouring calves were observed to be more likely to shed rotavirus and E. coli positive for K99 than appropriately matched nonscouring calves from the same farms. A comparison of an indirect fluorescent antibody test for K99 with a commonly used serological method for screening for enterotoxigenic E. coli found no significant relationship between the results of the two tests.