The Importance of the Periconception Period: Immediate Effects in Cattle Breeding and in Assisted Reproduction Such as Artificial Insemination and Embryo Transfer

Abstract

In livestock breeding, the successful outcome is largely depending on the "periconception environment" which, in a narrow sense, refers to the genital tract, where gametogenesis and embryogenesis occur. During these early stages of development, gametes and embryos are known to be particularly sensitive to alterations in their microenvironment. However, as the microenvironment somehow reflects what is going on in the external world, we must widen our definition of "periconception environment" and refer to all events taking place around the time of conception, including metabolic state and health and nutrition of the dam. In modern dairy cows that have to manage an optimal reproductive performance with continued growth and high milk yield, the periconception period is particularly challenging. The metabolic priority for growth and lactation is known to generate adverse conditions hampering optimal ovarian function, oocyte maturation, and development of embryo/fetus. In addition, by using artificial reproductive technologies (ARTs), gametes and/or embryos of livestock are exposed to unnatural conditions outside the male and female genital tract. Artificial insemination, the most widely used technique, is currently yielding pregnancy rates similar to natural mating, and calves produced by AI are equally viable after natural mating. In contrast, other ART, such as multiple ovulation and embryo transfer, have been reported to induce changes in gene expression and DNA methylation patterns with potential consequences for development.Finally, the "periconceptional" environment has been shown to not only influence the successful establishment of pregnancy but also the long-term health and productivity of the offspring. Hence, the optimization of management around the time of conception might open doors to improve animal production and product quality.

Programming of Embryonic Development

“…In addition, underfed and overfed sheep had altered serum insulin, insulin-like growth factor-1, leptin, progesterone, and (or) estradiol concentrations, indicating they were affected metabolically as well [23,80]. Other studies reported decreased rates of fertilization with IVF and (or) decreased rates of early embryonic development in ewes or cows fed a low-(nutrient-restricted) or high-(ad libitum intake) energy diet during the periconceptual period [81][82][83][84][85]. Conversely, others have shown that an altered plane of nutrition during the periconceptual period had either positive or no effects on blastocyst formation and/or embryo health in sheep [83,86].…”

The impact of stress and selected environmental factors on cows’ reproduction

“…The selection of cows for reproductive traits has contributed to the achievement of better reproductive rates in herds (Eetvelde et al 2017;Stangaferro et al 2018). The health of the cows, proper nutrition of animals, metabolic status, as well as environmental conditions has an impact on the reproductive success and health of the calves (Eetvelde et al 2017).…”

“…Recent research presents that the use of assisted reproductive techniques may reduce the reproductive performance of dairy cattle (Figueiredo et al 2020). It had been proved that IVP embryos (in vitro embryo production) are characterized by darker cytoplasm due to the higher content of lipids, slower growth, and more frequent occurrence of apoptosis compared to in vivo embryos (Eetvelde et al 2017). Moreover, the use of these techniques exposes gametes and/or embryos to different environmental conditions than those in the female and male reproductive systems (Eetvelde et al 2017).…”

“…This method shows similar conception rates to natural mating. In order for the treatment to be effective, the symptoms of oestrus must be detected earlier (Eetvelde et al 2017).…”

Senescence and Apoptosis During in vitro Embryo Development in a Bovine Model

“…Despite many improvements made in the field of assisted reproduction, in vitro embryo production systems are still not as efficient as in vivo development (Rizos et al, 2017). Notwithstanding, it should be emphasized that gametes and embryos are exposed to spatial and temporal unnatural conditions during ART, whose consequences are not completely known (Van Eetvelde et al, 2017). In cattle, approximately 90% of oocytes cultured in vitro undergo nuclear and cytoplasmic maturation, from which 80% are fertilized and cleave at least once (Lonergan et al, 2003).…”