Effects of ewe live weight and age on reproductive performance, lamb growth, and survival in Central Anatolian Merino sheep

Abstract. The aim of this study was to evaluate the effects of premating ewe weight and age on ewe reproductive performance, lamb growth and survival in Central Anatolian Merino (CAM) sheep.

The trial included 4935 ewes and 5548 lambs from 23 breeder flocks in Eskişehir Province. The live weights (LWs) and ages of the ewes were recorded 1 week before the mating season. The number of lambs born, fertility rate, multiple birth rate (MBR), and lamb survival rate (SR) at days 75 and 120 were determined. The effects of the LW and age of the ewe were found to be important for the reproductive performance of ewes and for the lamb's growth rate (P < 0.05–0.001). Ewe MBRs and the birth weight (BW) and LW of the lambs at days 75 and 120 increased proportionally with the increase in LW in ewes prior to mating. The fertility rate and MBR were lower (P < 0.05–0.001) in 1.5-year-old ewes than in older ewes. However, lambs' SR at days 75 and 120 were not affected by the premating LW and age of the ewe. In summary, a better reproductive performance and lamb growth rate in CAM flocks may be achieved by the selection of breeding ewes from ewes weighing more than 60 kg.