Responses to fleece weight selection and heritability estimates of wool characteristics in Romney sheep.
Body weight, fleece weight and wool characteristics were recorded for 2987 Romney hoggets, progeny of 114 sires, born over 9 breeding seasons. The hoggets were from a flock selected for high fleece weight and an unselected control flock. The selected flock had higher values for body weight (8.3%), clean fleece weight (24.3%) and fibre diameter (by 1 µm) than the control flock (P<0.001). Heritability estimates for spring body weight, greasy fleece weight, clean fleece weight, yield, fibre diameter, staple length, staple strength, loose wool bulk and brightness were 0.49, 0.33, 0.34, 0.39, 0.55, 0.40, 0.30, 0.44 and 0.14 respectively. The high selection differential achieved in the first year resulted in a non-significant genetic gain in greasy fleece weight over the 9 years.