Sexual activity of Romanov-Karakul crosses under semi-arid conditions
During 1973 87,5 x 12,5 and 75 25% Romanov – Karakul crosses were tested twice daily by vasectomized rams in order to determine their breeding season, anoestrous period, the length of the oestrous cycle and the duration of oestrus. During May the ovulation rate was recorded by laporatomy. The experiment was carried out with penned ewes on a maintenance ration. The procedure was repeated during 1974 with 50 x 50 and 25 x 75 % Romanov – Karakul crosses. Puberty was also determined in the 87,5 % and 75 % Romanovs by testing them twice daily for first oestrus and determining body mass at first oestrus. This was done from 60 days of age until the end of the first breeding season. All the crosses displayed oestrous activity from middle January to August. A deep anoestrus existed from September to the first half of January during which no more than 17,9 %of the possible oestrous cycles were exhibited. The length of the oestrous cycle did not differ from the Karakul but the oestrous period was significantly longer. The ovulation rate (number of ova/ewe/oestrus) decreased from 2,2 in the 85% Romanovs to 1,4 in the 25% Romanovs. Puberty occurred some two months before purebred Karakuls in the two crosses evaluated.