EFFECT OF INJECTIONS OF TESTOSTERONE PROPIONATE ON DOMINANCE RELATIONSHIPS IN A GROUP OF COWS

In a group of eight heifers, four animals whose social ranks were 2, 4, 6, and 8 were injected with testosterone propionate for 70 days. They all became dominant over controls and did not modify their own relationships among themselves. This experiment was replicated 3 months after the end of the first treatment with the same group; animals whose ranks were 2, 4, 6, and 8 at the beginning of the second experiment were treated. Again they all became dominant over controls and did not modify their relationships among themselves. Eighty percent of relationships modified by the first or the second treatment remain unchanged without any hormonal support for 4 to 10 months. A first analysis of social interactions does not seem to indicate a higher increase in the frequency of aggressive interactions in treated animals. © 1978.