Reduction in milk yield associated with somatic cell counts up to 600 000 cells/ml in French Holstein cows without clinical mastitis

摘要: Abstract The reduction in milk yield (kg) on test day associated with individual somatic cell count (SCC) up to 600 000 cells/ml was assessed using monthly cow-records collected for a 1-year period 105 Holstein herds located western France. Monthly records SCC over cells/ml, and/or occurring after clinical case of mastitis were excluded. resulting dataset comprised 32 148 from 4968 cows. A mixed autoregressive linear model used assess, day, the effects (dependent variable) herd-season (random), (after natural logarithmic transformation), days which recorded and an interaction term between milk. Regression coefficients expressed as polynomial kg increase calculated deviation reference value set at 50 000 function recorded. In primiparous cows, 0.30 100 000 0.61 200 000 1.09 cells/ml. multiparous increased parity For cows 2 50 pp, 0.32 0.63 1.13 50, 0.92 150 1.77 250 pp. ≥3 0.60 1.07 1.85