A STUDY OF SUBCLINICAL MASTITIS IN TWO HERDS, ONE MANAGED ORGANICALLY, THE OTHER CONVENTIONALLY, AND THE EFFECT OF DIFFERENT MANAGEMENT STRATEGIES

Mastitis in two herds managed as a comparison between organic and conventional dairy farming systems was monitored for 9 years utilising regular bacterial culture of milk samples, individual and bulk somatic cell counts and observation by farm staff. The most important isolates in pure cultures were coagulase-negative staphylococci, Staphylococcus aureus, Streptococcus uberis, and Bacillus spp. Positive cultures were generally not associated with subclinical mastitis. The objective was to develop strategies for the control of mastitis in organic cows without the use of antibiotics. Within a set of key control measures, two management strategies were trialled, one of which reduced the prevalence of subclinical mastitis to very low levels