ABSTRACT
The animal releases volatile odors into the surrounding atmosphere, most of which are waste products of metabolism in which emission of some compounds closely related to reproductive activities are termed as chemical signals (Hradecky 1975). The estrus-related odors are present only during the preestrus and estrus stages. These chemical signals have been reported to be volatile and nonvolatile molecules that are perceived through the main or accessory olfactory system (Brennan and Keverne 1997; Tirindelli et al. 1998). In mammals, structurally and anatomically, the olfactory systems are classified into two types: the MOS and the accessory olfactory system (AOS), specialized for the detection and transmission of pheromonal information (Halpern and Marinez-Marcos 2003; Mucignat-Caretta et al. 2012).
