Reducing the age at first calving, while still reaching rearing targets, will help to improve LDY. Studies carried out by the ILVO in Belgium18 showed that a reducing of age at first calving from 26 to 24 months reduces methane emission of dairy cows by 3.1%. It has also been demonstrated that heifers that calve at 22 to 24 months have optimal fertility and maximum milk yield in their first and second lactation19.

To reach an optimal milk production per lactation, a dairy cow must deal with the transition to lactation. A resilient dairy cow is defined as a cow that deals with transitions successfully, increasing the chances to express all her genetic potential to produce milk. Studies carried out by the ILVO in Belgium18 showed that increasing the production per day by 3kg will reduce methane emission by up to 8.4%.

Traditionally, a calving interval of 365 days is targeted, to ensure that cows can be dried off and prepared for the next lactation by the time their milk yield starts dropping. In highly productive herds, cows can be in strong negative energy balance after calving, making it more difficult to get them pregnant. Particularly if persistence of milk production is high, aiming at short calving interval may have a negative impact on farm economics and animal welfare20, so farm could also aim at a longer calving interval of up to 415 days.

Functional longevity is defined as the ability of a cow to avoid culling due to reasons other than poor milk production15,16,17. Studies carried out by the ILVO in Belgium18 showed that reducing the culling rate by 5% and increasing milk production by 3kg per day reduces emission of methane by 11.7%. Good transition cow management is key to avoid involuntary culling later in lactation.