The optimum age at first calving is 22 months
Reducing the age at first calving, while still reaching rearing targets, will help to improve Lifetime Daily Yield because heifers will start producing at an earlier age. Studies carried out by the ILVO in Belgium18 showed that reducing the age at first calving from 26 to 24 months resulted in a reduction of methane emission of 3.1%. A study carried out at the Kempenshof research center19 demonstrated that heifers that calve at 22 to 24 months have optimal fertility and maximum milk yield in their first lactation, resulting in a further improvement of Lifetime Daily Yield.