Efecto del recuento de células somáticas sobre la longevidad funcional del ganado frisón analizado mediante técnicas de análisis de supervivencia. (Effect of somatic cell scores on functional longevity of dairy cattle assessed by survival analysis.)

The objective of this study was to analyze the effect of somatic cell scores on functional longevity (FL) assessed using survival analysis. Longevity was measured as days of productive life. Functional longevity was obtained by global longevity correcting for milk production. Data of production and somatic cell count (SCC) consisting of records from 20.359 Spanish Holstein cattle, with date of first calving between 1988 and 2000. Factors included in the Weibull model were: herd-year-season of calving (HYS), age at first calving (AFC), lactation number-stage of lactation (NS), annual change in herd size (CHZ), milk (MY), fat (FY) and protein (PY) yield. All the effects were significant (P