ABSTRACTThis study evaluated the effects of shearing at 50 days of gestation on the productive, reproductive and response to a gastrointestinal parasite challenge of male offspring from weaning (104 d) to 18 months old. In total, 79 Polwarth male lambs were used, 44 single (S) and 35 twin (T) born to ewes either shorn at 50 days of pregnancy (PS, n =41) or shorn at 62 days post-partum (U, control, n = 38) resulting in four sub-groups: SPS: single male lambs born to ewes shorn at 50 days of pregnancy (n = 23), SU: single male lambs born to postpartumshorn ewes (n = 21), TPS: twin males lambs born to ewes shorn at 50 days of pregnancy (n = 18) or TU: twin female lambs born to postpartum shorn ewes (n = 17). The lambs were kept together on improved pasture throughout the entire experiment. Body weight, body condition score and fecal eggs count were recorded every 14 days from weaning to 18 months old.Ultrasound measurements in vivo were performed at 12.5 months and 14.6 months old to estimate of ribeye area (REA) and backfat thickness (BFT) in the ongissimus dorsi muscle and the thickness of fat in the hip region (P8).Furthermore, plasma testosterone concentration was determined once every two weeks to establish the age at onset of puberty. PS male lambs were heavier (P = 0,02) than U male lambs. Shearing treatment had no effect on none of the parameters of body development (P ˃ 0,05). However, REA (P = 0.06) and P8 (P = 0,02) were higher at 14.6 mo than 12.5 mo old. Testosterone concentration, age at puberty and testicular weight were not different (P ˃ 0,05) among treatments. Single male lambs reached puberty earlier (P = 0.06) than twin. Prepartum shearing did not affect the parasite egg count and the Famacha index. The study concludes that ewe shearing at 50 days of gestation positively influences the bodyweight of male offspring from weaning onwards but not the other evaluated traits