Mastitis in Canada

The Canadian Bovine Mastitis Research Network has launched a Canadian-wide study of mastitis in Canada. 291 herds registered with Canadian Dairy Herd Improvement were chosen at random, and the incidence of mastitis-causing bacteria in bulk milk collected from these herds was determined. The incidence of different bacteria in the milk of cows affected with clinical mastitis is also being determined. Bacteria tested for included Staphylococcus aureus, Streptococcus agalactiae, Escherichia coli and mycoplasmas. Only three out of 291 farms recorded positive results for S. agalactiae in bulk milk samples, and no positive results for mycoplasmas were recorded. However 50-60% of farms recorded positive results for S. aureus in bulk milk, although significant variations in the incidence of S. aureus in different provinces were recorded. In the Maritime provinces, 65-70% of herds tested positive for S. aureus in bulk milk samples, compared with only 25% in British Columbia. 120 dairy farms from each province are also taking daily milk samples from cows affected with clinical mastitis over a one-year period. To date, the bacteria most frequently isolated from these samples have been S. aureus, streptococci, E. coli and coagulase negative staphylococci. Practices that may limit the spread of mastitis are briefly considered, including the use of gloves during milking, and disinfecting teats after milking..