Effect of weaning age on feedlot performance of lambs and reproductive traits of Zel breed ewes

The present study aimed to determine the proper weaning age of Zel lambs. For this purpose, ninety male and female lambs (average live body weight =2.57±0.41 kg) selected and were divided into three groups (each group = 30). The experimental treatments were; 1. weaning at an average age of 60 days, 2. 75 days, or 3. 90 days. The lambs were introduced to fattening program and were fed with iso-energetics and iso-nitrogenous diets until 6 months of age. The dam’s ewe of all groups enters to mating program two months after parturition and ewe lambing data contain dam’s weight, lamb’s mortality, litter size, lamb’s birth weight, and sex were recorded. Results showed that dry matter intake (DMI) and feed conversion ratio (FCR) did not affect by weaning age of lambs. The lambs that weaned at 60 days old, had higher average daily gain (ADG) at fattening period, then lambs were weaned at 75 and 90 days old, significantly. The parturition rate, prolificacy rate, lambing rate, and litter size of groups weaned at 60, 75, and 90 days of age were 88, 81, and 85; 119, 118, and 117; 104, 96, and 100; and 19, 18, and 17% respectively, and did not observed significant between the treatments. It concluded that Zel lambs weaned at 60 days old, could increase growth performance compared to elder lambs, and improves the reproductive performance of ewe.