Synchronization with estradiol benzoate in the presence of the corpus luteum in Wagyu cows increases the number of medium follicles but does not interfere with in vitro production of embryos

Abstract

Reproductive biotechnologies are emerging as an important element for livestock; however, some strategies must be modified to adapt to different breeding systems, such as the use of follicular synchronization protocols. This study aimed to evaluate follicular synchronization using estradiol benzoate (EB), in the presence of the corpus luteum (CL) from Wagyu oocyte donors in in vitro embryo production (IVEP). Rounds of IVEP were performed in heifers and cows (n=19) that were classified into three groups: G1/CL - animals with CL, G2/WCL - animals without CL, and G3/CL + EB - animals with CL that were subjected to follicular synchronization with EB at D0. The groups G1/CL and G2/WCL were considered the control and undertook the natural process of follicular dynamics. The results showed that the synchronization of the follicular wave with the application of EB in the presence of CL, presented a smaller number of small (6.05 ± 0.55) and large follicles (0.45 ± 0.15), but increased (P < 0.05) the number of medium-sized follicles (16.20 ± 0.90). However, the results of ovum pick up showed that regardless of whether or not EB was applied, and regardless of the presence or absence of CL in the Wagyu donor, there was no difference among the groups (P > 0.05) concerning the number of viable oocytes and the viability rate. It was concluded that follicular synchronization using EB in Wagyu oocyte donors that presented a CL, increased the number of medium-sized follicles. However, there was no improvement in the efficiency of ovum pick up, in vitro embryo production, and pregnancy rate.

Fluazuron Influences the in vitro Production Embryos of Wagyu Cow

“…However, it is reported that despite the significant effects found, the values obtained in this study are similar to those reported in other studies carried out with Wagyu donor cows. In a study whose objective was to investigate the follicular synchronization using estradiol benzoate, with the presence of the corpus luteum, in bovine female donors of Wagyu oocytes, in in vitro embryo production, Zamai et al (2021) observed total oocyte values between 10.50 and 12.83, viability rate around 74%, total embryos produced between 2.40 to 2.85 and blastocyst rate between 19.16 to 26.44%. However, it is considered that the number of total and viable oocytes obtained in the studies Zamai et al (2021), regardless of treatment, was lower than those reported in the literature for other races (SARTORI et al, 2016), showing an inferiority in this aspect for Wagyu donors.…”

“…In a study whose objective was to investigate the follicular synchronization using estradiol benzoate, with the presence of the corpus luteum, in bovine female donors of Wagyu oocytes, in in vitro embryo production, Zamai et al (2021) observed total oocyte values between 10.50 and 12.83, viability rate around 74%, total embryos produced between 2.40 to 2.85 and blastocyst rate between 19.16 to 26.44%. However, it is considered that the number of total and viable oocytes obtained in the studies Zamai et al (2021), regardless of treatment, was lower than those reported in the literature for other races (SARTORI et al, 2016), showing an inferiority in this aspect for Wagyu donors. However, despite this finding, the other reproductive advantages of Wagyu females stand out, such as sexual precocity, ease of delivery, maternal ability and longevity.…”