Hair cortisol in swine: a new matrix for the study of adrenal function in field condition

A new matrix, i.e. hair, has been recently utilized for the evaluation in some species of mean cortisol level as an indicator of chronic stress condition. In order to assess the validity of this approach for swine, we collected and analyzed bristles from 30 sows housed in a breeding farm, over two successive reproductive cycles. Our data gave clear indication of the reliability of this matrix, indicating, in both cycles, a higher activation of the adrenal response during late pregnancy, delivery and early lactation. Furthermore from our data it is possible to presume the existence of a seasonal variation of cortisol level, with the lowest values recorded during the hot season. It would be interesting to evaluate if this reduction in cortisol level during the hot season plays a role in seasonal infertility of swine.