A study investigating the incidence and associated risk factors of heifer mastitis in the Macalister Irrigation District

© 2013 Lauren Jane ClyneThe project aimed to assess the incidence, causative pathogens and risk factors for mastitis in primiparous heifers in the Macalister Irrigation District (MID). Additional aims included analysis of the effect of mastitis on production, lactation length and risk of removal from the herd. Data was collected from 19 farms over a period of two years. This included a retrospective analysis of data collected in 2009, and prospective data collection in 2010. Information such as management practices, treatment records, individual cow cell counts, production data, cull records and bulk milk cell counts were collected in both years. Additional data gathered in 2010 included microbiological culture results from both clinical and subclinical cases of mastitis, and recording of health events. Overall 11.3% of the heifer cohort in this study suffered from at least one case of clinical mastitis (CM) during the first lactation. Heifers were particularly at risk of mastitis early in lactation, with 65.7% of cases occurring within 30 days in milk, compared to 37.7% in mature cows in the same period. Strep. uberis was the bacteria most commonly isolated from quarter cases of clinical mastitis (48.1%) and from heifers diagnosed with subclinical mastitis (15.6%). The use of an internal teat sealant pre-partum had the greatest effect on the odds of CM within 30 days of calving (CM0-30d) (OR 0.44 CI 0.28-0.68 P<0.001) followed by calving in 2010 (OR 1.71 95% CI 1.31-2.33 P