A genetic analysis of maternal behaviour score in Scottish Blackface sheep

Under field conditions, ewe behaviour was quantified by maternal behaviour score (MBS)-a six-point scale which assesses ewe flight distance when lambs are handled for the first time, within 24 h of birth (adapted from O'Conno r et al., 1985). MBS was measured on 847 Scottish Blackface ewes on two exp erimental hill farms, over a maximum of four parities. Live weights of lamb s born to these ewes were measured at birth, marking (average age of 42 day s) and weaning (average age of 120 days). MBS was significantly higher (P <0.05) for ewes with more lambing experienc e (multiparous ewes), for older ewes and for twin-bearing ewes compared wit h ewes with single lambs. MBS was under genetic control (h(2) = 0.13, perma nent environmental effect = 0.19, when analysed as the same trait across pa rities) and the repeatability was 0.32. MBS had no significant effects on weight gain of lambs. However, a moderate , positive genetic correlation tons estimated between MBS and the average w eight gained by lambs from birth to marking (r(g) = 0.4, s.e. 0.22), althou gh the genetic correlation estimated between MBS and weight gained to weani ng was close to zero (r(g) = 0.02, s.e. 0.16). Ewes with a MBS of 1 (ewe fl ees and does not return to her lambs) had significantly more lambs dying be fore marking and weaning than ewes with a higher maternal behaviour score. Selection to reduce the proportion of ewes in this category may therefore b e beneficial.