Pilot study into milk haptoglobin as an indicator of udder health in heifersafter calving

Mastitis, inflammation of the mammary gland, is often caused by intramammary infection with bacterial or-ganisms. It impacts on dairy cattle welfare, production, udder health and longevity in the herd. Current detectionmethods for mammary inflammation and infection all have limitations, particularly for on-farm diagnosis ofnon-clinical mastitis after calving. Acute phase proteins have been suggested as alternative early indicators of thedisease and can potentially be used as cow-side test with results in real time. In this study, milk haptoglobinconcentrations were investigated over thefirst week postpartum to explore haptoglobin's potential as indicatorof udder health in dairy heifers. Haptoglobin concentration was highest on day 3 of lactation, and was positivelycorrelated with somatic cell count, a commonly used marker of inflammation (rs= 0.68). Haptoglobin level wasalso associated with bacteriological culture results, a key indicator of infection status, whereby median hap-toglobin concentration on days 3 and 5 was higher in quarters that were infected at calving than quarters thatwere non infected at calving. Sensitivity and specificity of haptoglobin concentration as indicator of infectionwere low, both for lenient and strict culture-based definitions of intramammary infection (57 or 60% and 61 or63%, respectively). Although haptoglobin was a poor biomarker for intramammary infection with coagulasenegative staphylococci in heifers during thefirst week after calving, it may have value as an indicator of majorpathogen infections, particularly in large scale dairy herds where pre-partum heifers are managed off-site.