Social Dominance in Gilts

Abstract

Three experiments were conducted with 36 pregnant gilts to determine the existence of social dominance. When adequate feeder space was provided, there was no evidence of a dominance order, position of penmates at the feeder space failing to show a regular pattern. However, with inadequate feeder space, a dominance order was manifested by biting and pushing. In a group of seven gilts, one gilt completely dominated all but one within the pen, and another failed to exhibit any evidence of aggressiveness (biting). The other gilts in the group arranged themselves in a definite order of descending dominance in terms of the number of penmates bitten. Using four of these animals and three strange gilts, these results were confirmed. In addition, individual bouts between pairs were observed by introducing two animals into a pen with one feeder space. These observations confirmed the rank order previously indicated by study of the entire group. Therefore it appears that a definite dominance order is established in small herds of gilts. The aggressive behavior which results in the order is exacerbated by providing inadequate feeder space. The data also suggest that, in a limited feeding program with sows or gilts, aggressive behavior may contribute to within-pen variation. Techniques which would reduce the manifestation of aggressive behavior would tend to minimize such within-pen variation. Copyright © . .