The effect of organic status and management practices on somatic cell counts on UK dairy farms

The numbers of organic dairy farms are increasing in the United Kingdom and in other parts of the world. On organic farms, the use of veterinary medicines is restricted. Because of this, there is concern that cow health is poorer on these farms. As udder health is primarily maintained by the use of antimicrobials, the effect of organic status on mastitis and somatic cell counts (SCC) is important to investigate. The aim of this study was therefore to determine whether the organic status and other management factors affect SCC. A group of 80 dairy farms was used in the study: 40 organic farms and 40 nonorganic farms. The farms were recruited in pairs, and each organic:nonorganic pair was matched for herd size, housing type, genetic merit for milk production and geographical location. Somatic cell count data were extracted from national databases for a standard year (2004), and analyzed using stepwise logistic regression models. The organic status of the farm did not appear in the final model, indicating no major influence of organic status on SCC. There were, however, several effects of management on SCC. Somatic cell counts were lower on farms where the udders were not cleaned or cleaned only when dirty. Somatic cell counts were also lower on farms that kept cows in larger management groups and where the majority, but not all cases of mastitis are treated with antimicrobials. It can be concluded that the control measures used on the organic farms in this study are at least as effective as those used on nonorganic farms in controlling SCC. Other management factors are influential and attention to these factors will allow farmers to reduce SCC.