Genetic analysis of emotional reactivity in sheep: effects of the genotypes of the lambs and of their dams

Abstract

Abstract A total of 1347 weaned lambs from eight genotypes were tested over five consecutive years: Romanov (ROM) and Lacaune (LAC) pure breeds, the two F1 crossbreeds (RL and LR) and the offspring of ewes from these four genotypes sired with Berrichon-du-Cher rams (BCF). The lambs were individually exposed to three challenging tests involving novelty, human contact and social isolation. Ten synthetic variables were used to express social reactivity (<it>i.e</it>., active <it>vs</it>. passive strategy), exploratory activity and reactivity to humans. BCF crossbreds were more active (<it>i.e</it>., high bleats, locomotion and attempts to escape) than purebreds and F1. In contrast, ROM expressed more passive responses (<it>i.e</it>., low bleats and vigilance postures) than LAC and BCF crossbreds. In addition, ROM approached a motionless human less and had longer flight distances to an approaching human than did LAC and BCF crossbreds. When restrained, ROM, and to a lesser extent B×ROM and B×LR, avoided human contact more than did LAC, RL and B×LAC. Most of these differences were explained by direct additive genetic effects while maternal influences or heterosis effects were rarely significant. The highest heritability was for high bleats (<it>h</it>²= 0.48). Females were more active and avoided human contact more than did males.