Pregnant mares and post-weaning foals are often fed concentrates rich in soluble carbohy­ drates, together with forage. Recent studies suggest that the use of concentrates is linked to al-terations of metabolism and the development of osteochondrosis in foals. The aim of this study was to determine if broodmare diet during gestation affects metabolism, osteoarticular status and growth of yearlings overfed from 19 to 24 months of age and/or sexual maturity in prepubertal colts. Twenty-four saddlebred mares were fed forage only (n= l2, group F) or cracked barley and forage (n=12, group B) from mid-gestation until foaling. Colts were gelded at 12 months of age. Between 20 and 24 months of age, all yearlings were overfed (+140% of requirements) using an automatic concen-trate foeder. Offspring were monitored for growth between 6 and 24 months of age, glucose ho-meostasis was evaluated via modified FSIGT at 20 and 24 months of age and osteoarticular status was investigated using radiographie examinations at 24 months of age. The structure and fonction of testicles from prepubertal colts were analyzed using stereology and RT-qFCR. Post-weaning weight growth was not different between groups. Testicular maturation was delayed in F colts compared to B colts at 12 months of age. From 19 months of age, the cannon bone was wider in B vs F yearlings. F yearlings were more insulin resistant at 19 months compared to B yearlings but B yearlings were affected more severely by overnutrition with recluced insulin sensitivity. The osteoarticular status at 24 months of age was not different between groups. In conclusion , nutritional management of the pregnant broodmare and the growing foal affects sexual maturity of colts and the metabolism of foals until 24 months of age. These effects may be deleterious for reproductive and sportive performances in older horses.