The studies were performed in 2008 on 308 sheep at the age of 2-4 years. Sheep from the following breeds were used: Karakachan, Tsigay, Replyan, Panagyurishte, Copper-red Shoumen, Karnobat, Pleven Blackhead, White Maritsa, Patch-faced Maritsa, Stara Zagora and Romanov. During the spri