Effect of selection for fleece weight on liveweight, reproductive performance and wool characteristics in mixed age Romney ewes

This paper presents the analysis of 3525 annual production records of mixed age Romney ewes in a fleece weight selected (HF) or control (RC) flock over 11 years. HF ewes were significantly (P<0.001) heavier than RC ewes for autumn live weight (8%), winter live weight (9%), spring live weight (7%), greasy fleece weight (20%) and clean fleece weight (19%). Small but significant (P<0.01) flock differences were found for fibre diameter and yellowness. HF fleeces were coarser and more yellow than RC fleeces. HF ewes were significantly (P<0.01) higher than RC for ovulation rate (1.80 vs 1.73 SED 0.03), number of lambs born/ewes lambed (1.63 vs 1.56 SED 0.02), and number of multiple births/ewes lambed (60% vs 54% SED 2%), but lower (P<0.01) for number of lambs weaned/ lambs born (0.84 vs 0.88 SED 0.01). The results indicate that single trait selection for fleece weight enhances greasy and clean fleece weights, live weight and ovulation rate, with an associated increase in FD and yellowness of their fleeces.