Risk factors for culling in Holstein-Friesian dairy cows.

Risk factors associated with voluntary and involuntary culling within a Holstein-Friesian dairy cow research herd were identified. Data were studied from 3498 completed lactations from the Langhill Holstein-Friesian dairy herd between January 1990 and June 2008. During this period the cows were based on two different farms in Scotland. The culling rate of the milking herd was approximately 25 per cent per annum. Approximately 68 per cent of cows culled were classified as involuntary. The association between different risk factors and the incidence of culling was investigated using a general linear mixed model. Of the 838 cows culled, 59 per cent were culled before the fourth lactation. Culling was associated with cows that had an assisted calving (P<0.01), aborted (P<0.01) and/or suffered from mastitis (P<0.05). Cows that were culled were also more likely to be older cows (P<0.01), have a low number of milking days (P<0.001) and/or a greater number of days from calving to conception (P<0.01). Culling was also associated with conception failure (r=0.752, P<0.001). Further work might help reduce the number of animals culled involuntarily, by identifying key factors associated with the incidence of an assisted calving, abortion and mastitis, and improving milking and fertility performance using detailed data from the Langhill herd.