Biotechnical control of oestrus in Slovak Tsigaya sheep during anoestrus phase of reproductive cycle

This work is focused on oestrus induction and synchronization of Slovak Tsigaya (SC) ewes during anoestrus phase out of breeding season. In four experiments (E1-E4) oestrus synchronization was carried out with 12-day application of both the Chrono-gest vaginal sponges (preparations on the basis of synthetic gestagen, 40 mg FGA - fluorogestone acetate) and Sergon inj. a.u.v. (preparation on the basis of the serum chorione gonadotropin hormone - eCG, 500 i.u.). The experiments with inductions and synchronization of oestrus and preparation of breeding rams for mating were established in the last ten days of April and continued up to the first ten days of May. Natural mating by rams began the second day after withdraw of the vaginal sponges and were broken on the 25th May. The sheep-breeding animals were reared for slaughter production of milk lambs for the pre-Christmas market. In the experiments (E1-E2-E3) the ewes of flocks were divided into two parts - treated groups (207-301-300 ewes) and non-treated groups (543-467-150 ewes). The results of these observations are as follows: There were significantly more pregnant no treated sheep in experiment E3 than in experiments E1 and E2. On the contrary the number of lambing ewes (fertility) from treated sheep was significantly different between experiment E1 and experiments E2 and E3. The same significant differences were found in the number of lambs born per number of mating ewes (fecundity) in treated groups between experiment E1 and experiments E2 and E3. Mutual differences in natality (number of lambs born per one-hundred lambing ewes) between all experiments (El, E2 and E3) were no significant. The differences in number of the born twins and triplet lambs between all three experiments were mutually significant. In the experiment E2 there were most litters (32.4 %) with more lambs among treated ewes. The results suggested that the parameters of the flocks reproduction are dependent from number of sheep per one breeding ram and quality of the rams' preparation for mating. In the experiment shearing of the treated sheep during installation of the vaginal sponges influenced E4 obtained results. This kind of manipulation of the animals caused lost of the vaginal sponges in 16.9 % and were pregnant only 76.6 % treated sheep.