Factors Affecting the Efficiency of In Vitro Embryo Production in Prepubertal Mediterranean Water Buffalo

Abstract

Embryos from prepubertal water buffalo can be produced using laparoscopic ovum pickup (LOPU) and in vitro embryo production (IVEP). However, to date, it is unclear what factors and environmental conditions can affect LOPU-IVEP efficiency in prepubertal animals, especially buffalo. In this study, we explored the impact of season, age and individual variation among female donor animals, as well as the effect of the sire used for in vitro fertilization. Donor animals between 2 and 6 months of age were stimulated using gonadotropins prior to LOPU, which was performed at two-week intervals. Following in vitro maturation and fertilization, the resulting embryos were then cultured to the blastocyst stage until they were either vitrified or transferred into recipient animals. The number of follicles available for aspiration and embryo development rates was stable throughout the year. As animals became older, there was a slight trend for fewer COCs recovered from LOPU and better embryo development. There was a large individual variation in both ovarian response and the developmental competence of oocytes among donors. The bull used for fertilization also had a significant impact on embryo development. Upon embryo transfer, pregnancy rates were not affected by the number of embryos transferred per recipient. The best pregnancy rates were achieved when transferring blastocysts, compared to compact morula or hatched blastocysts. Finally, vitrification had no effect on pregnancy rate compared to fresh embryos.

Phenotypic and Genetic Analyses of In Vitro Embryo Production Traits in Chinese Holstein Cattle

“…For example, Zeron et al [6] found that the number of oocytes per ovary in Holstein cattle in spring and winter was significantly higher than that in summer and autumn. The IVEP traits showed a similar trend in water buffalo, with the exception of the number of cumulus-oocyte complexes [7]. Generally, poor OPU performances were observed in summer, and operation season partly explains the phenotypic variation in embryo production efficiency [8,9].…”

“…Generally, poor OPU performances were observed in summer, and operation season partly explains the phenotypic variation in embryo production efficiency [8,9]. In addition, the effects of other factors, such as donor age, donor parity and physiological status, diet, and gonadotropin stimulation, on oocyte collection and embryo production have also been noted in a few reports [7,[10][11][12]. In China, dairy cattle are challenged by serious heat stress in summer [13].…”

Transient suppression of Wnt signaling in poor-quality buffalo oocytes improves their developmental competence

“…Adept implementation and use of assisted reproductive technologies (ARTs) have been suggested as measures to overcome these physiological limitations and for the fast propagation of superior germplasm (4)(5)(6)(7). Despite the availability of highly optimized culture conditions and techniques for the stringent quality selection of oocytes, the in vitro embryo production (IVEP) technology in buffalo has not been very successful (8,9). Such optimized methodologies that are otherwise successful in cattle often result in only a meager percentage of buffalo oocytes reaching the blastocyst stage (10,11).…”

“…ovarian morphology, season, donor, culture conditions, hormones, and oocyte quality among others (7,(12)(13)(14). Besides, the low efficiency of multiple-ovulation and embryo transfer (MOET) often attributed to low fertility and poor response to superovulation further decrease the success rate of buffalo IVEP (4,9). The identification and selection of good-quality oocytes (high competence) is a crucial step for ensuring their complete maturation and subsequent embryonic development, which is critical for successful IVEP (15)(16)(17).…”

Impact of epidermal growth factor and/or β-mercaptoethanol supplementations on the in vitro produced buffaloes' embryos

“…Compared to cows, the donner buffaloes were known to give lower ovarian follicles numbers, a low embryo recovery rate, and less effective superovulation ( 3 ), which may be attributed to the genetic-merits advancements through reproduction-biotechnologies of the cows compared to buffaloes ( 4 , 5 ). In-vitro embryo production (IVEP) is an effective technique for producing high-quality bovine embryos ( 6 ).…”