The purpose of present study was to determine the possibility and degree of synchronization of estrus by the “ram effect” in West Balkan Mountain sheep breed. An experiment has been carried out for three years and covers a total of 902 ewes aged 18 months to 6 years old. In each flock of 150-180 ewes there were placed in three ram teasers, which were isolated from ewes for 8 months The introduction of rams in the flock was during the transition to estral period and for the first two years it was on first of August and in the third year of experiment – on 18th August (early estral season). The ewes which came in estrus were artificially inseminated with fresh semen, shallow-cervical. The date of insemination and lambing for each ewe were recorded. In the first 15 days after introduction of ram 22% of all ewes came in estrus, which were apparently naturally cycling. From 16 to 28 days of introduction of rams 58% of ewes came in estrus, hence reacted to the effect of ram. The second characteristic peak of the ram effect was significantly higher than the first. Ewes that were naturally cycling also responded to the effect of the ram. By applying the ram effect 40% of ewes lambed within two weeks. Barren ewes were relatively high at an average of 9%, with ranges from 5 to 14% of all ewes during different years. From the barren ewes 67% were not getting pregnant next year too. This justifies their culling.
K. Nedelkov, N. Todorov, A. Kolev, T. Marinkov