Addressing neonatal diarrhea and antibiotic use in dairy calves

点击翻译按钮获取中文摘要

The dairy industry is an important economic sector in Canada, and animal health greatly influences economic performance. Diarrhea is a common problem in dairy calves, and while a variety of bacterial (e.g. E. coli, Salmonella), viral (e.g. rotavirus) and parasitic (e.g. Cryptosporidium) causes have been well-studied, the cause of diarrhea is often not diagnosed and outbreaks on farms are not uncommon. Difficulties diagnosing (and preventing) diarrhea could be because of interactions between microorganisms (coinfections); disease that occurs as a result of microbial population disturbances, not the effects of sole organisms ('dysbiosis'), changes in disease patterns of known pathogens or emergence of new pathogens or strains. This study will involve a large dairy operation in Ontario that produces approximately 750 calves per year. Despite modern management practices and exceptional production of milk and high quality genetics, calf diarrhea rates have been very high. In 2014, 92% of calves were treated for diarrhea. Calf mortality was 5%, with rates reaching 25% at some points during the year. Extensive diagnostic testing has failed to implicate the 'traditional' calf diarrhea pathogens and preliminary evaluation of farm records indicates a very high incidence of antibiotic use, resulting in high economic costs, high labour costs for administration and concerns about risks for development of antimicrobial resistance. This study will evaluate the cause of diarrhea on this farm, as a way to improve calf health and economic production on the farm, as well as to provide a broader understanding of this industry-wide problem. It will do so by using novel techniques to evaluate the composition of the bacterial population in the intestinal tract (the 'microbiota') as well as specific targeting of bovine coronavirus based on preliminary data suggesting this virus is present at high rates in diarrheic calves compared to healthy controls. It will also develop and test an antimicrobial use algorithm to standardize and improve antibiotic administration, to improve treatment of calves and reduce antibiotic use (thereby optimizing calf health and reducing the likelihood of antibiotic resistance.)