Abstract

The objective of this work was to evaluate the concentration of fecal metabolites of corticosterone and to verify if there are differences between dominant and subordinate heifers. The feces of 18 buffalo heifers were collected in the estrous period, to quantify the corticosterone concentrations. The heifers were separated into three groups (G1, G2 and G3) and synchronized. The observations of the social and sexual behaviors were recorded and, from these results, the sociometric matrix was constructed to establish the social index and determine the hierarchic positions of the buffalo heifers as low, moderate and high. The fecal concentrations of corticosterone were higher in animals with high hierarchic position on day zero and describe alterations in the dominant females before synchronization, suggesting that there is an energy cost for the females in the highest position to be able to maintain their dominance status.

Key words: Estrus, hormones, social status, non-invasive technique.