Resumen
- A particular emphasis has been put, by farmers, on the conformation and management of cows milked once a day (OAD). These factors might alter the culling decisions of herds after shifting from twice a day (TAD) to OAD milking. A Cox proportional hazard model was implemented to identify factors that influenced the survival of cows after the shift from TAD to OAD milking for three consecutive seasons (2013–2015). Overall, non-pregnant cows and those with low milk yield and low milk solids yield had a higher likelihood of being culled than more productive and pregnant cows. Holstein-Friesian and crossbred cows had a higher likelihood of being culled compared with Jerseys. Cows with better adaptability to milking (score > 7), and those with low pins/steeper rumps (score ≥ 4) and better udder support (score ≥ 6) were less likely to be culled. For traits such as body capacity and leg conformation, intermediate scores were associated with a lower likelihood of culling. Besides body capacity and udder support, traits including adaptability to milking, rump angle and leg conformation could also potentially be included in a new selection index for OAD dairy cattle.