EARLY PREDICTORS OF DOMINANCE ABILITY IN HEIFERS (BOS TAURUS, L.) OF THE HERENS BREED

Many studies have looked for predictors of dominance in various species. However, to our knowledge only short term predictors have been investigated. Cows of the Hérens breed have been selected for fighting tendency and dominance ability; therefore these animals constitute an original and pertinent model to study the possibility of predicting dominance ability at an early age. Physical characteristics, several aspects of social behaviour, reactivity to fear eliciting situations, docility towards humans were assessed in 28 heifers at 6 and 18 months of age. These heifers were reared from birth in 5 permanent groups which never met. Dominance of the 28 subjects was estimated at 30 mo. by observing each heifer in a succession of seven groups that each contained 4 unacquainted animals. The 28 heifers were then allocated to 2 classes (dominant or subordinate) by means of a cluster analysis. Early indicators (combinations of variables) of adult dominance ability were assessed among the variables measured at 6 and 18 months, by a succession of linear discriminant analyses. The discriminant function which best predicts the dominance class either at 6 or 18 mo. includes mainly variables from the fear eliciting tests. This function allows accurate prediction of the dominant or subordinate position of heifers in 94.7 and 92.2% of the cases respectively. The less fearful a heifer was at either 6 or 18 months, the more dominant she tended to be at 30 months of age. These results are in accordance with the previously reported importance of emotional reactivity in dominance relationships in cattle.