Days in Milk at Culling in Holstein Dairy Cows

This study presents the overall culling reasons and also the days in milk at culling in Holstein dairy cows. Data regarding to all exits of cows from the herd were collected during 1996 until 2006 in 7 large commercial Holstein farms. Each exiting cow has been characterized by demographic data, production data and culling reason. The reasons for culling were grouped into 8 logical groups including sold for dairy purposes, low milk production, feet and legs problems, reproductive problems, death, mastitis, disease and udder problems. The dependent variable of interest was the number of days between calving and culling. The data on the Days In Milk (DIM) when a cow was culled for the defined category were analyzed using General Linear Models. The distribution analyze for when a cow was culled during the lactation period was done using the statistical software package JMP (SAS Institute Inc., NC, USA). The result showed that the most frequent primary culling reasons were diseases and reproductive problems. Parity at culling averaged 3.5. Calving-to-culling interval averaged 217.16 days and its distribution showed a progressive decrease in frequency. Days in milk at culling was impacted by the culling category (p < 0.001). Days in milk at culling for cows which culled due to udder problems and mastitis were the lowest and for reproductive problems was the greatest compare with the other categories. Days in milk at culling was impacted by the parity groups (p < 0.001) and was greatest for primiparous and lowest for the multiparous cows (p < 0.001). High producer cows had greatest days in milk at culling (p < 0.001). The result of this study demonstrated that almost half of the culls occurred due to diseases. The result also demonstrated that cows were culled at different stage of lactation according to the culling category.