Impact of different doses of a preparation with gonadotropic action on reproductive parameters in ewes in the estrous season

Tsvetomira Bancheva; Svetoslava Stoycheva

Tsvetomira Bancheva

, Svetoslava Stoycheva

Abstract: The study was conducted to determine the effect of the administration of different doses of PMSG (Pregnant mare's serum gonadotropin) on reproductive performance in ewes of the Staroplaninski Tsigai breed.
The experiment was conducted at the beginning of the estrous season (July-August) on 30 Staroplaninski Tsigai ewes. 3 groups of 10 animals were formed (1 control and 2 experimental groups). Induction of synchronous estrus was performed with vaginal tampons containing 60 mg of medroxyprogesterone acetate (MAP). In both experimental groups, the vaginal tampons remained in the ewes vagina for 12 days, and on the day of removal of the tampons, the ewes of the 1st experimental group were injected with 400IU PMSG and those of the 2nd experimental group 500IU group. Animals in the control group were not treated according to the above scheme. The insemination was natural with siring rams, by the hand release method.
In the ewes of the 1st experimental group (400IU), estrus was synchronized in 100% of the animals at the 56th hour. While in the 2nd experimental group (500IU), the estrous synchronization was recorded in 90% of the animals, with one ewe did not show any estrous traits and was not inseminated. In the control group, which included non-treated animals according to the adopted estrous synchronization scheme, no ewes were recorded in estrus and were not inseminated.
The results show that the two doses of gonadotropin (400UI and 500UI) increased the studied reproductive indicators in Staroplaninski Tsigai ewes, at the beginning of the estrous season. The following values of the reproductive indicators were reported in the two experimental groups: 1st experimental group - fertility – 90.0%, 155.5% biological fecundity and 44.4% twinning; 2nd experimental group - 70.7% fertility, 150.0% biological fecundity and 33.2% twinning. The gestation length of ewes in the present study averaged 146 days.

Keywords: estrous season; estrous synchronization; ewes; fecundity; fertility; PMSG

Citation: Bancheva, Ts. & Stoycheva, S. (2025). Impact of different doses of a preparation with gonadotropic action on reproductive parameters in ewes in the estrous season. Bulg. J. Agric. Sci., 31(1), 199–204.

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Date published: 2025-02-25

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