Fertility of a farm has a direct impact on age at first calving and on the calving interval.
With fertility being an important reason for culling, it also has an impact on the number of lactations of a dairy cow. An important fertility parameter is the calving interval.
Traditionally, the aim is to have a calving interval of 365 days or less, so 1 calf per cow per year. This ensures that cows can be dried off and prepared for the next lactation by the time their milk yield starts dropping. It also ensures genetic progress is made.
In highly productive herds, cows can be in strong negative energy balance during the first few months after calving, in which case it might be difficult to get them pregnant within 115 days after calving. Particularly if persistence of milk production is high, the impact on the lifetime production of keeping the calving interval short seems ignorable and may have a negative impact on farm economics and animal welfare20. Farms could also aim at a longer calving interval of up to 415 days. This reduces the risk that cows get too fat at the end of lactation. More and more farmers use an individual optimal calving interval for each cow.