Implementation of strategies for mastitis control in dairy herds in Macedonia: A case report

Mastitis is probably the most common and costly disease in modern dairy cow husbandry. The aim of the present paper was to report the results concerning udder health after implementation of a specific strategy using both field and laboratory methods. During the period June 2010-December 2011 a total of 674 dairy cows from four dairy farms were included in the investigation. Clinical mastitis was diagnosed by detection of signs of inflammation in the udder, while subclinical mastitis was diagnosed at the animal level by an increased Somatic Cell Count (SCC) using laboratory tests, and subsequently confirmed at quarter level by California Mastitis Test (CMT).Microbiological analysis of the milk samples was carried out by standard procedures using Gram staining, biochemical tests and automated identification system.The distribution of somatic cell counts on cow level (n=674) was:305 (45.3%) with SCC less than 100,000SCC/mL, 236 (35.0%) 100,001 - 350,000 SCC/mL, and 133 (18.7%) with more than 350,000SCC/mL. From a total of 1684 quarters tested by CMT, 644 quarters (38.2%) were positive and 1040 quarters (61.8%) were negative. In 60 out of 101 quarters that had a positive CMT result and no current treatment and that were sampled for bacteriology, bacteria could be isolated. Main bacteria identified, were coagulase - negative staphylococci (40.0%), Streptococcus agalactiae was present in 25.0%, Escherichia coli in 16.6%, Proteus spp. in 11.7% and Staphylococcus aureus in 6.7% of the bacteriological positive samples. After introducing specific mastitis-control measures, focusing on milking hygiene, dry-off treatment, and antibiotic treatment of both clinical and sub-clinical mastitis cases, the prevalence of subclinical mastitis was reduced from 38.2to 10.8%, while the incidence of clinical mastitis decreased from 21.0% to 4.9%.In conclusion, the implementation of a standard mastitis control plan based on a regular assessment of the somatic cell count can reduce the prevalence of clinical and sub-clinical mastitis in dairy herds.