Effectiveness of progestagens and prostaglandin-based protocols for oestrus synchronisation in Ouled Djellal ewes during the non-breeding season in north-eastern Algeria

Aim of study: This study aimed to evaluate the effectiveness of short- and long-term progesterone- and prostaglandin-based protocols for oestrus synchronisation in Ouled Djellal ewes during the non-breeding season. The main objective was to identify the most efficient hormonal strategy to enhance reproductive performance under seasonal anoestrus conditions. Area of study: The study was conducted in a semi-arid agroecological area (Souk Ahras) in Algeria, where Ouled Djellal sheep are a predominant local breed. Material and methods: A total of 128 healthy, multiparous Ouled Djellal ewes were divided into six groups. Three groups received progestagen-based treatments: 7-day progesterone (P4Short), 14-day progesterone (P4Long), and 7-day progesterone with GnRH at sponge insertion (GP4Short). Two groups received double prostaglandin injections: 2PGF2α and 2PGF2α+ GnRH. The sixth group served as an untreated control. Reproductive parameters included oestrus onset and response, pregnancy, fertility, conception rates, and litter size. Blood samples were collected at four time points to assess progesterone (P4) levels, and natural mating lasted 40 days. Main results: Oestrus onset and response were comparable between P4Short and P4Long groups, but GP4Short achieved the highest oestrous response (100%), pregnancy rate (91.7%), and fertility (87.5%). At day 5, P4Short Group recorded the highest P4 level (3.33 ± 0.82 ng/mL), while GP4Short Group peaked at day 18 (8.48 ± 1.20 ng/mL), both indicating successful ovulation, unlike control group. Research highlights: Short-term progestagen protocols, especially when combined with GnRH, proved most effective for improving reproductive performance in Ouled Djellal ewes during seasonal anoestrus.