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'Connor et al., 1985). MBS was measured on 847 Scottish Blackface ewes on two experimental hill farms, over a maximum of four parities. Live weights of lambs born to these ewes were measured at birth, marking (average age of 42 days) and weaning (average age of 120 days).

MBS was significantly higher (P < 0.05) for ewes with more lambing
experience (multiparous ewes), for older ewes and for twin-bearing ewes
compared with ewes with single lambs. MBS was under genetic control (h2 =
0.13, permanent environmental effect = 0.19, when analysed as the same
trait across parities) 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 weight gained by lambs from birth to marking (r(g) = 0.4, s.e. 0.22), although the genetic correlation estimated between MBS and weight gained to weaning was close to zero (r(g) = 0.02, s.e. 0.16). Ewes with a MBS of 1 (ewe flees and does not return to her lambs) had significantly more lambs dying before marking and weaning than ewes with a higher maternal behaviour score. Selection to reduce the proportion of ewes in this category may therefore be beneficial.