The late age at first calving from the French Charolais breeds is associated with both economic and environmental costs which could be partly mitigated by improving the sexual precocity of heifers. This study investigates the environmental and genetic determinism of age at puberty (AP) in this breed and characterize the relationships between sexual precocity and pre- and post-weaning performance. A total of 650 Charolais heifers, raised on two different farms and born over a 4-year period were used. Puberty was determined by progesterone assay and growth was followed up to 2 years of age, ending with a feed efficiency trial. Mean AP was 16.7 months. Heifers born in spring were more precocious than those born in winter. Age at puberty was moderately heritable (0.21 ± 0.08). It was unfavorably genetically correlated with birthweight (0.30 ± 0.21) but favorably with growth before weaning (−0.30 ± 0.23). A trend for a positive genetic relationship between feed efficiency and AP (0.40 ± 0.44) was observed. Overall, a good strategy to improve sexual precocity in French Charolais cows could be to prioritize spring birth season and good rearing conditions for heifers, while selecting for reduced birth weight and increased growth rate.
Taussat et al. (2026) studied this question.