Ann. Méd. Vét., 2005, 149 (3), pp 173-182 A comparison of somatic cell count and antimicrobial susceptibility of subclinical mastitis pathogens in organic and conventional dairy herdsBOUTET P., DETILLEUX J., MOTKIN M., DELIEGE M., PIRAUX E., DEPINOIS A., DEBLIQUY P., MAINIL J., CZAPLICKI G., LEKEUXAbstract :
Bovine subclinical mastitis is the most important disease affecting dairy cows. The fluctuating
increase in somatic cell count (SCC) that occurs causes major economic losses in dairy industry.
This comparative study between conventional and organic dairy herds was conducted in the aim
to better characterize which consequences might have different management practices on SCC
but also on the frequency of pathogens isolated and their antimicrobial susceptibility. Four conventional and four organic herds, with bulk milk SCC >300x103cells/ml were selected, in which respectively 47 and 44 cows were investigated. Each quarter was sampled 3 times at 15 days interval for SCC, microbiological analysis and antimicrobial susceptibility. In both herd categories, major pathogens isolated were by order of importance Streptococcus uberis, Staphylococcus aureus and Streptococcus dysgalactiae with a great impact on SCC. Coagulase negative staphylococci were the most frequent minor germs and had a moderated but real impact on SCC. In certified organic dairy farms, the three most frequently isolated major pathogens were significantly more susceptible to antimicrobials in vitro. This study suggests that the limited use of antibiotics in organic dairy herds could explain, at least in part, the lower resistance obtained from analysed isolates. Get the PDF Contact person : philippe.boutet@ulg.ac.be |