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Croatian Veterinary Journal, Vol. 57 No. 3, 2026.

Original scientific paper

https://doi.org/10.46419/cvj.57.3.8

Gonadotropin regimen and dose predict superovulatory ovarian response in Ouled Djellal ewes: a stepwise regression study

Ramzi Lamraoui orcid id orcid.org/0000-0001-9952-627X ; Department of Biology of Living Organisms, Faculty of Natural and Life Sciences. University of Batna 2, Batna (05110), Algeria *
Yamina Belkhiri ; Department of Biology of Living Organisms, Faculty of Natural and Life Sciences. University of Batna 2, Batna (05110), Algeria
Djallel Eddine Gherissi orcid id orcid.org/0000-0003-1615-1658 ; Laboratory of Animal Productions, Biotechnologies and Health, in Institute of Agronomic and Veterinary Sciences, University of Souk-Ahras, Souk-Ahras (41000), Algeria
Farida Afri-Bouzebda ; Laboratory of Animal Productions, Biotechnologies and Health, Institute of Agronomic and Veterinary Sciences, University of Souk-Ahras, Souk-Ahras (41000), Algeria
Zoubir Bouzebda ; Laboratory of Animal Productions, Biotechnologies and Health, in Institute of Agronomic and Veterinary Sciences, University of Souk-Ahras, Souk-Ahras (41000), Algeria
Aziza Ferag ; Laboratory of Science and Techniques for Living, University of Souk-Ahras, Souk Ahras (41000), Algeria
Faicel Chacha orcid id orcid.org/0000-0002-8089-8214 ; Biotechnology Research Center, Constantine, Algeria
Souheyla Benbia orcid id orcid.org/0000-0002-9558-1711 ; Department of Biology of Living Organisms, Faculty of Natural and Life Sciences. University of Batna 2, Batna (05110), Algeria

* Corresponding author.

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Abstract

This study aimed to evaluate the effects of gonadotropin regimen (PMSG alone vs. PMSG + GnRH or PMSG + hCG) and dose on superovulatory responses in 35 Ouled Djellal ewes during the breeding season. Intravaginal sponges containing 40 mg fluorogestone acetate were inserted for 14 days in all ewes. Two days before sponge removal, ewes were randomly assigned to seven treatment groups differing by regimen and dose. Outcomes were corpora lutea (CL) count, anovulatory follicles (AF), ovulation rate (OR), and serum progesterone (P4). Associations were assessed using stepwise regression analysis. Ewes receiving PMSG + GnRH or PMSG + hCG exhibited stronger ovarian responses than those given PMSG alone. Final stepwise models explained 41.3% of variance in CL, 20.5% in AF, 27.10% in P4, and 23.60% in OR. In each model, molecule type entered first and contributed more to model fit than dose, indicating that regimen exerted a greater influence than dose escalation. In conclusion, combining PMSG with either hCG or GnRH improves ovarian response parameters and overall model predictability compared with PMSG alone. These findings support evidence-based optimisation of superovulation protocols in Ouled Djellal ewes to enhance prolificacy, increase embryo yield, and accelerate dissemination of elite genetics in advanced breeding programmes.

Keywords

Ouled Djellal breed; superovulation; PMSG; hCG; GnRH; progesterone; ovulation rate; stepwise regression; embryo transfer

Hrčak ID:

345261

URI

https://hrcak.srce.hr/345261

Publication date:

15.5.2026.

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