Effects of lambing season, birth type and sex on early performance of lambs

The effects of lambing season, birth type and sex on growth performance were studied using 249 Balouchi lambs (94 winter‐born and 155 spring‐born lambs) under farm conditions. The lambs were weighed within 12 h of birth, at 60 (weaning) and 120 days of age. Body measurements (heart girth [HG], height at withers [HW] and body length [BL]) were determined at weaning and at 120 days of age. Lambs born in the winter were heavier than those born in the spring at 60 ( P < 0.01) and 120 ( P < 0.05) days of age by 1.53 and 1.76 kg, respectively. Ram lambs were heavier ( P < 0.01) than ewe lambs at 60 and 120 days of age by 1.7 and 3.43 kg, respectively. Single‐born lambs were heavier than those born as twins at birth ( P < 0.01), 60 and 120 ( P < 0.05) days of age by 0.50, 1.18 and 1.99 kg, respectively. Winter‐born lambs had a higher average daily gain (ADG) than spring‐born lambs ( P < 0.05). Ram lambs had a higher pre‐weaning and overall ADG ( P < 0.01) compared with ewe lambs. Single lambs had a higher ADG ( P < 0.05) at pre‐weaning than twin lambs.