Vet World   Vol.18   November-2025  Article - 20 

Optimizing pregnant mare serum gonadotropin dosage for reproductive efficiency and lamb survival in Dorper × Assaf ewes during the non-breeding season

Background and Aim: Reproductive efficiency during the non-breeding season is a critical factor influencing year-round productivity in sheep farming, particularly in semi-arid environments. Pregnant mare serum gonadotropin (PMSG) is commonly used to induce estrus, yet the optimal dosage that maximizes fertility and lamb growth while minimizing hormonal side effects remains unclear. This study aimed to determine the optimal PMSG dose for enhancing reproductive and growth performance in Dorper × Assaf crossbred ewes under semi-extensive conditions in Palestine.

Materials and Methods: A total of 143 non-lactating Dorper × Assaf ewes (aged 2–3 years) were synchronized with intravaginal progestagen sponges for 14 days, followed by intramuscular administration of 400, 500, or 600 international units (IU) of PMSG. Key reproductive traits, estrus response, conception rate, abortion rate, fecundity, and lamb survival, were recorded, alongside lamb birth and weaning weights. Data were analyzed using a one-way analysis of variance and a general linear model incorporating parity, litter size, and sex effects, with significance set at p < 0.05.

Results: High conception and lambing rates were observed across all groups. The 400 IU PMSG dose resulted in the lowest abortion rate (2.44%) and highest lamb survival (96.9%), while higher doses (500–600 IU) increased abortion incidence without improving fertility outcomes. Birth weight increased with PMSG level (3.42–3.83 kg), whereas weaning weight peaked at 500 IU (22.18 kg). Litter size and lamb sex significantly affected both birth and weaning weights, with singletons and males being heavier.

Conclusion: Administering 400 IU of PMSG provides the optimal balance between reproductive performance, lamb survival, cost-efficiency, and animal welfare. Excessive hormonal stimulation at higher doses offers no additional reproductive benefit and may compromise ewe health. Implementing this moderate, breed-specific hormonal protocol enhances fertility while reducing veterinary intervention and production costs, promoting sustainability and welfare-conscious management. These outcomes directly contribute to sustainable development goals (SDG) 2 – zero hunger and SDG 12 – responsible consumption and production, advancing resilient and ethical small-ruminant farming systems.

Keywords: Animal welfare, Dorper × Assaf ewes, estrus synchronization, lamb survival, pregnant mare serum gonadotropin dosage, reproductive efficiency, sustainable development goals 12, sustainable development goals 2.

---

How to cite this article: Halawa W, Bensouf I, Khnissi S, Salman M, Khaleel M, and M’Hamdi N (2025) Optimizing pregnant mare serum gonadotropin dosage for reproductive efficiency and lamb survival in Dorper × Assaf ewes during the non-breeding season, Veterinary World, 18(11): 3561-3570.

Received: 10-07-2025   Accepted: 24-10-2025   Published online: 27-11-2025

Corresponding author: Ikram Bensouf    E-mail: bensoufikram2@gmail.com

DOI: 10.14202/vetworld.2025.3561-3570

Copyright: Halawa, et al. This article is an open access article distributed under the terms of the Creative Commons Attribution 4.0 International License (http://creativecommons.org/licenses/by/4.0/), which permits unrestricted use, distribution, and reproduction in any medium, provided you give appropriate credit to the original author(s) and the source, provide a link to the Creative Commons license, and indicate if changes were made. The Creative Commons Public Domain Dedication waiver (http:// creativecommons.org/publicdomain/zero/1.0/) applies to the data made available in this article, unless otherwise stated.