Improving the breeding capabilities of short-term estrus synchronized Ossimi sheep using Pregnant Mare Serum Gonadotropin loaded chitosan-nanoparticles

Ahmed M Shehabeldin¹Maha S Salama²Mohamed E A Omar²Liza A Abdel-Rafaa²Mohey A Ashour³Mahmoud A E Hassan³Abdelghany A El-Shereif⁴Mohamed Kamel Abdelmegeid⁵Mustafa Shukry^6*Ahmed Elolimy⁷

• ¹Animal Reproduction Research Institute, Agricultural Research Center (Egypt), Giza, Beni Suef, Egypt
• ²Animal Production Research Institute (APRI), Giza, Beni Suef, Egypt
• ³Agricultural Research Center (Egypt), Giza, Giza, Egypt
• ⁴Department of Plant Protection, Faculty of Agriculture, Alexandria University, Alexandria, Alexandria, Egypt
• ⁵College of Information Technology, United Arab Emirates University, AlAin, Abu Dhabi, United Arab Emirates
• ⁶Department of Physiology, Faculty of Veterinary Medicine, Kafrelsheikh University, Kafrelsheikh, Egypt
• ⁷College of Agriculture and Veterinary Medicine, United Arab Emirates University, AlAin, Abu Dhabi, United Arab Emirates

The present study evaluated the efficacy of pregnant mare serum gonadotropin (PMSG) and PMSG encapsulated in chitosan-tripolyphosphate nanoparticles in enhancing reproductive performance in short-term progesterone estrus-synchronized Ossimi ewes. Seventy-five healthy ewes were randomly assigned to three groups (n = 25 per group). Group 1(representing current standard practice) received 25 mg progesterone acetate for 7 days, 600 IU PMSG on day 6, and 250 µg prostaglandin F2α (PGF2α) on day 7. Group 2 followed the same regimen as Group 1, except for administering 300 IU of PMSG-loaded chitosan-tripolyphosphate nanoparticles on day 6, followed by an intramuscular injection of 250 µg PGF2α on day 7. Group 3 received 150 IU of PMSGloaded chitosan-tripolyphosphate nanoparticles on day 6 and 250 µg PGF2α on day 7. Estrus detection occurred between days 7 and 11, with a gonadotropin-releasing hormone (GnRH) injection at breeding. Group 1 had a significantly shorter onset of estrus (54.40 ± 4.50 h; p < 0.05) compared to Group 2 (71.60 ± 0.51 h) and Group 3 (72.20 ± 4.81 h). Pregnancy and lambing rates were highest in Group 2 (100%; p < 0.05), and Group 2 produced more fetuses (40) than Group 1 (30) and Group 3 (25). Fecundity was also highest in Group 2 (160%; p < 0.05).Follicular diameter was greater in Group 2 on day 9, although the number of large follicles was similar across groups. The number of corpora lutea significantly increased on day 7 compared to day 0 in all groups.Progesterone levels peaked on day 7 and declined by day 9 across all groups. These results suggest that administering 300 IU of PMSG encapsulated in chitosan-tripolyphosphate nanoparticles can enhance reproductive performance more effectively than conventional PMSG, offering a promising strategy to improve fertility in shortterm progesterone-synchronized ewes.