پردیس کشاورزی و منابع طبیعی دانشگاه تهران Iranian Journal of animal Science 2008-4773 56 2 2025 06 22 Comparison of short-term and long-term estrus synchronization methods using progesterone and their effect on pregnancy rate: A meta-analysis study Comparison of short-term and long-term estrus synchronization methods using progesterone and their effect on pregnancy rate: A meta-analysis study 465 478 99616 10.22059/ijas.2024.383143.654029 FA Omid Bouzari Department of Animal Science, Faculty of Agriculture, University College of Agriculture and Natural Resources, University of Tehran 0000-0002-5052-3753 Mahdi Zhandi Department of Animal Science, Faculty of Agriculture, University College of Agriculture and Natural Resources, University of Tehran, Karaj, Iran 0000-0003-2886-9747 Journal Article 2024 10 02 This study presents a meta-analysis comparing the effectiveness of short-term and long-term progesterone-based protocols for estrous synchronization in sheep, focusing on pregnancy rates. The primary aim was to evaluate whether short-term protocols, which are more practical, yield comparable results to traditional long-term methods in terms of pregnancy success. The study is based on a meta-analysis of 22 independent studies conducted between 2010 and 2023, which examined various progesterone-based estrous synchronization protocols in different seasons. The data was collected from Scopus, PubMed, OpenAlex, and Google Scholar databases using keywords such as "progesterone", "P4", "estrous”, “synchronization," "sheep," and "ewe." The results revealed no significant difference between short-term and long-term protocols concerning pregnancy rates. This suggests that both protocols are equally effective, with short-term protocols offering logistical and cost benefits. However, the analysis also highlighted moderate heterogeneity among the studies, indicating that factors like breed, nutrition, and environment might influence outcomes. This meta-analysis provides valuable results into the effectiveness of short-term versus long-term progesterone-based estrous synchronization protocols in sheep. The findings indicate that short-term protocols are just as effective as long-term protocols in achieving pregnancy, offering significant advantages in terms of cost and labor efficiency.  Additionally, potential publication bias was identified, underscoring the need for further research in this area to refine these reproductive strategies. This study presents a meta-analysis comparing the effectiveness of short-term and long-term progesterone-based protocols for estrous synchronization in sheep, focusing on pregnancy rates. The primary aim was to evaluate whether short-term protocols, which are more practical, yield comparable results to traditional long-term methods in terms of pregnancy success. The study is based on a meta-analysis of 22 independent studies conducted between 2010 and 2023, which examined various progesterone-based estrous synchronization protocols in different seasons. The data was collected from Scopus, PubMed, OpenAlex, and Google Scholar databases using keywords such as "progesterone", "P4", "estrous”, “synchronization," "sheep," and "ewe." The results revealed no significant difference between short-term and long-term protocols concerning pregnancy rates. This suggests that both protocols are equally effective, with short-term protocols offering logistical and cost benefits. However, the analysis also highlighted moderate heterogeneity among the studies, indicating that factors like breed, nutrition, and environment might influence outcomes. This meta-analysis provides valuable results into the effectiveness of short-term versus long-term progesterone-based estrous synchronization protocols in sheep. The findings indicate that short-term protocols are just as effective as long-term protocols in achieving pregnancy, offering significant advantages in terms of cost and labor efficiency.  Additionally, potential publication bias was identified, underscoring the need for further research in this area to refine these reproductive strategies. https://ijas.ut.ac.ir/article_99616_5b0ebd596f6b9afa67f4f05c410a59d0.pdf