Arena behaviour of Merino weaners is heritable and affected by divergent selection for number of lambs weaned per ewe mated

ABSTRACT Data of 3375 6.5-month-old Merino weaners from two divergently selected lines at Elsenburg were used to evaluate the genetics of the response of weaner lambs to flock isolation and a stationary human in an arena test. The High (H) line was selected upwards and the Low (L) line was selected downwards for number of lambs weaned per ewe mated (NLW) from 1986 to the present. Selection resulted in divergent lines for NLW, live weight up to yearling age, wrinkle scores as well as other breech strike indicator traits such as breech and crutch cover scores. Weaners from the H line (selected for NLW) travelled longer distances in the arena, based on the number of squares crossed. They also bleated at a lower frequency and urinated and defecated at a lower frequency than their L line contemporaries (all P