Combining two injectable progesterone formulas for estrous synchronization in ewes.

The study aimed to evaluate the effectiveness of combining two injectable progesterone (iP4) formulas for estrous synchronization in ewes and to compare it with traditional intravaginal progesterone devices. Additionally, the study assessed whether the inclusion of GnRH enhances the reproductive outcomes of the iP4 treatment. Two experiments were conducted. In the first experiment, 20 Santa Inês ewes were divided into two groups: one group received intravaginal progesterone devices, and the other received combined long-acting and short-acting iP4. In the second experiment, 30 Corriedale ewes were divided into two groups: one received the combined iP4 with GnRH, and the other without GnRH. Estrous, ovulation, follicular populations, and progesterone concentrations were monitored. The combined iP4 treatment induced an artificial luteal phase and produced reproductive responses similar to those obtained with intravaginal devices. In the first experiment, the iP4 treatment tended to result in more synchronized ovulation compared to the control (P=0.095). In the second experiment, adding GnRH enhanced the quality of the corpus luteum, as indicated by increased diameter and vascularization on Day 23 (P=0.047 and P=0.02, respectively). The combined administration of long-acting and short-acting iP4 effectively synchronized estrous in ewes and showed similar efficacy to traditional intravaginal devices. The inclusion of GnRH improved luteal quality, suggesting potential benefits for reproductive management in ewes. Further studies are needed to evaluate the fertility outcomes of these protocols under field conditions.

The pFSH dose affects the efficiency of in vivo embryo production in Santa Inês ewes.

This study compared the follicular growth, superovulatory response, and in vivo embryo production after administering two doses of porcine follicle-stimulating hormone (pFSH) in Santa Inês ewes. The estrous cycle of 36 multiparous ewes was synchronized with the Day 0 protocol and superovulated with 133 mg (G133, n=18) or 200 mg (G200, n=18) of pFSH. Ultrasonographic evaluations of the ovaries were performed, ewes were mated and submitted to non-surgical embryo recovery. Viable blastocysts were stained with Nile Red and Hoechst. The G200 had a greater number of medium and large follicles, as well as a larger size of the third largest follicle. A total of 97.2% (35/36) of the ewes came into estrus and it was possible to transpose cervix in 80.6% (29/36). There were no effects of treatments in the response to superovulation, the proportion of ewes in which was possible to transpose the cervix, the number of corpora lutea, the number of anovulatory follicles, the proportion of ewes flushed with at least one recovered structure, number of recovered structures, number of viable embryos, viability rate, and recovery rate. The G200 ewes were in estrus for a longer period of time than the G133 ewes (54.0 ± 4.5 h vs. 40.3 ± 3.6 h) and produced more freezable embryos (6.5 ± 1.6 vs. 2.3 ± 0.7) than G133. Both doses promoted an efficient superovulatory response and did not affect embryonic lipid accumulation. The dose of 200 mg of pFSH showed greater potential to increase the superovulatory response, as it increased follicular recruitment and the recovery of freezable embryos.