Анотация: The purpose of these studies was to determine the effectiveness of the salt-free-salt diet, which is widely applied in Bulgaria as a non-hormonal method for oestrus synchronization of ewes. The main point of this diet consists of complete deprivation from salt in ewe`s diet for approximately two weeks followed by the addition of 15-20 g dietary salt per ewe per day for 5-7 days. Three group experiments have been carried out. The first experiment was conducted with Tsigai ewes, the second - with Karakachan Sheep, and the third group experiment has been carried out with ewes of the Bulgarian Dairy Synthetic Population. The animals of same breed were divided into two groups equalized by age and BCS. Both groups were placed at the same conditions of feeding and keeping. Control groups received regularly salt, while experimental groups was subject to the salt-free-salt diet