Comparative post-breeding outcomes in jennies inseminated with cryopreserved semen re-extended in seminal plasma or treated with platelet-rich plasma.

Artificial insemination (AI) with cryopreserved semen in donkeys is challenging due to poor fertility, likely caused by an exacerbated post-breeding inflammatory response. This study evaluated the effects of frozen-thawed semen re-extension in seminal plasma (SP) and intrauterine infusion of platelet-rich plasma (PRP) on post-breeding uterine inflammation, progesterone concentrations, and fertility in jennies. A total of 68 estrous cycles from 14 fertile jennies were randomly assigned to one of five groups: insemination with frozen-thawed semen reconstituted in 7 mL of SP (SP, n = 12); insemination with frozen-thawed semen followed by intrauterine infusion of Lactated Ringer's Solution (LRS) (Control, n = 14) or autologous PRP (PRP, n = 14) 6h post-AI; insemination with fresh semen (FS, n = 14); and sham-insemination with LRS following PRP infusion 6h post-AI (PRP.only, n = 14). Uterine lavage was performed 6h post-AI in all cycles. Intrauterine fluid accumulation (IUF), endometrial neutrophil counts (PMN), corpus luteum (CL) volume, and plasma progesterone concentration were assessed multiple times before and after AI. Pregnancy diagnosis was performed on Day 14. FS and SP groups had lower neutrophil counts 6h post-AI than Control and PRP groups (P < 0.05). PRP.only cycles had the lowest neutrophil counts at 6h and 24h post-AI (P < 0.05). Neutrophil counts were similar between all groups at 48h post-AI (P > 0.05). Plasma progesterone was higher in FS cycles on Days 3 and 8 compared to Control-assigned cycles (P < 0.05), and Day 14 compared to all groups (P < 0.05). CL volume and IUF were similar across groups (P > 0.05). Pregnancy rates were higher in FS cycles (71 %) compared to all other groups (Control, 0 %; PRP, 14 %; SP, 8 %; P < 0.05). In conclusion, SP reduced post-breeding inflammation but did not improve fertility outcomes in jennies AI with cryopreserved semen, while PRP had no effect. Additionally, plasma progesterone was affected by the type of semen used for AI but not by treatments.