Estimation of genetic and non‐genetic effects on productive life of Iranian Holstein dairy cows

Understanding the factors that influence the lifespan of dairy cows is crucial for enhancing their productive life (PL). This study aimed to investigate the impact of genetic and environmental effects on the PL of Holstein cows. Data included 82,505 cows from 1952 sires that calved for the first time between 2001 and 2016. PL was defined from first calving to culling. Proportional hazard models, assuming a piecewise Weibull distribution of the baseline hazard function, were utilized to account for time‐dependent effects, such as herd size variations, year‐season, milk yield, fat and protein contents, and the time‐independent fixed effect of age at first calving. Herd‐year and sire effects were considered as random effects. All effects showed significant associations with PL (p