Abstract: The physiological effects of the “ram-effect” has been extensively investigated

The vomeronasal organ (VNO) consists of paired, blind ending tubes on either side of the nasal septum. The VNO lumen connects to the nasopalatine canal and also to the oral and nasal cavities. The vomeronasal sensory epithelium is connected to the accessory olfactory bulb (AOB). The AOB in turn has a direct link to the hypothalamus. If the VNO and the accessory olfactory system do play a role in the detection of pheromones, females with a non-functional VNO would not be able to detect male pheromones. Therefore, theoretically, no or a very poor endocrine response should be detected in does after the introduction of males during the non-breeding season, while does with a functional VNO are expected to show an endocrine response. The aim of this study was evaluate the role of the VNO in the reproductive responses of does in terms of oestrus behaviour and conception rates subsequent to the introduction of bucks. The preliminary results, although not statistically significant, support this hypothesis. Only 20% of does with a non-functional VNO was pregnant while 56% of does with a functional VNO was pregnant after the introduction of bucks during the non-breeding season. Lower concentrations of oestradiol and LH were also observed in treated does compared to the controls. _______________________________________________________________________________________