Improving the breeding capabilities of short-term estrus synchronized Ossimi sheep using pregnant mare serum gonadotropin loaded chitosan-nanoparticles.

Abstract

INTRODUCTION: 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. METHODS: Seventy-five healthy ewes were randomly assigned to three groups (&#x202f;=&#x202f;25 per group). Group 1 (representing current standard practice) received 25&#x202f;mg progesterone acetate for 7&#x202f;days, 600&#x202f;IU PMSG on day 6, and 250&#x202f;&#x3bc;g prostaglandin F(PGF) on day 7. Group 2 followed the same regimen as Group 1, except for administering 300&#x202f;IU of PMSG-loaded chitosan-tripolyphosphate nanoparticles on day 6, followed by an intramuscular injection of 250&#x202f;&#x3bc;g PGFon day 7. Group 3 received 150&#x202f;IU of PMSG-loaded chitosan-tripolyphosphate nanoparticles on day 6 and 250&#x202f;&#x3bc;g PGFon day 7. Estrus detection occurred between days 7 and 11, with a gonadotropin-releasing hormone (GnRH) injection at breeding. RESULTS AND DISCUSSION: Group 1 had a significantly shorter onset of estrus (54.40&#x202f;&#xb1;&#x202f;4.50&#x202f;h;&#x202f;<&#x202f;0.05) compared to Group 2 (71.60&#x202f;&#xb1;&#x202f;0.51&#x202f;h) and Group 3 (72.20&#x202f;&#xb1;&#x202f;4.81&#x202f;h). Pregnancy and lambing rates were highest in Group 2 (100%;&#x202f;<&#x202f;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%;&#x202f;<&#x202f;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&#x202f;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 short-term progesterone-synchronized ewes.