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Published online by Cambridge University Press: 22 November 2017
Reproduction performances in cattle regularly decreased with time. For example, the number of inseminations per pregnancy increased in dairy herds from 1.43 to 1.75 and the calving interval (CI) from 385 to 412 days in 10 years (Leroy et al., 2006). Such a reduction is responsible for rising income losses for breeders. In Belgium, an increase of the age at first calving (AFC) by 3 months and of the CI by 20 days induced a gross margin reduction of about 500 € /cow/year.