In mid Jan, 40 ram‐lambs born in Oct were divided into 4 groups (n = 10): Group FA, exposed to 16 h of light for 2 months (15 Jan–15 Mar); Group SAR, housed with 3 adult sexually‐activated rams from 15 Mar to the end of the experiment; Group NAR, housed with 3 adult non‐activated rams from 15 Mar; and Group C, control, isolated from adult rams during the experiment. Adult rams were rendered sexually active by a exposing them to long days (16 h light) from 15 Jan to 15 Mar. Individual and group ram serving capacity tests were performed on 20 June, when ram‐lambs were 8‐month‐old, using 40 ewes synchronized in oestrus. For 20 min, each ram was exposed to 5 ewes, and the number of attempts of mounting and mountings were recorded. After that, rams were regrouped and the same observations of events, with the same 10 ewes used for the individuals test, were recorded. After that, ram‐lambs could mate the ewes for 48 h. GLM, anova and chi square tests were applied. During the individual tests, half of the attempts of mountings (6, 17, 22, and 55%, p < 0.01) and mountings (4, 15, 31, and 50%, for the FA, SAR, NAR and C groups, resp, p < 0.01) performed per ram were recorded in the control group. A similar distribution was observed in the group test (attempts of mounting: 9, 11, 24, 57%, mountings: 0, 18, 27, 55%, for the FA, SAR, NAR and C groups, resp, p < 0.001). However, fertility rate obtained by ewes mated by SAR (90%) and C (100%) ram‐lambs was higher (p < 0.01) than the FA (50%) and NAR (40%) groups. In conclusion, rearing autumn‐born ram‐lambs in isolation of adult congeners of the same species results in a high degree of sexual activity at 8‐months of age, although their fertility is similar to ram‐lambs reared in the presence of sexually‐active adult rams.