Advances and limitations of in vitro embryo production in sheep and goats

Abstract

This review summarizes the latest advances and main limitations for the implementation of in vitro embryo production programs in sheep and goats. We describe the laparoscopic assisted technique for oocyte retrieval and propose new insights for follicular manipulation to improve oocyte quality. Further description of the routine conducted in our laboratory for the in vitro process of oocyte maturation, fertilization and embryo culture is presented, with emphasis in the main issues for the success of the technique. Protocols for fixed time embryo transfer (FTET) are proposed and the optimal number of in vitro produced (IVP) embryos to be transferred per female is discussed. In addition, we present pregnancy outcomes and birth rates recently obtained with FTET with IVP embryos cryopreserved by vitrification with new minimum volume methods. In summary, due to important refinements for in vitro embryo production in sheep and goats achieved in the recent years, this technology is now available for its implementation in commercial programs for genetic improvement, for the production of genetically engineered sheep and goats, and for basic research in reproduction.

Impact of short nutrient stimuli with different energy source on follicle dynamics and quality of oocyte from hormonally stimulated goats

“…The morphofunctional ovary unit allows the interaction of different cell types capable of contributing to the complete development of oocyte during the folliculogenesis phase. Thus, the exponential proliferation of granulosa cells from gonadotrophin‐mediated hormone stimulation for antrum acquisition and improvements in oocyte competence becomes essential (Menchaca, Barrera, Santos‐Neto, Cuadro, & Crispo, ). Therefore, regardless of the type of treatment used, oocyte recovery rates observed in this study (72%) are consistent with the data obtained by other researchers (50%–91%) (Fernandes et al, ; Menchaca et al, ; Sanchez‐Lazo et al, ).…”

CRISPR in livestock: From editing to printing

“…The success of in vitro production implies that the IVEP laboratory should be capable to obtain good fertilization and cleavage rates (~80e90%) and should have optimum culture conditions to achieve acceptable in vitro development rates (~30e40% blastocysts). For further revision of the procedure for IVEP conducted in our laboratory, see previous review [29].…”

L-OPU in Goat and Sheep—Different Variants of the Oocyte Recovery Method

“…These reports show that the laparoscopic technique allows to perform different kinds of operation in a short time, especially in small ruminants. The shortening of the time of surgery in consecutive sessions (1)(2)(3)(4)(5)(6)(7)(8)(9)(10)(11)(12)(13)(14)(15)(16)(17) was the result of the increasing skills and better cooperation of surgeons. These observations were also noticed by other authors [28,29].…”

“…Endoscopic methods are used in breeding animals for recovering and transferring embryos, for intra-uterine insemination, and for diagnostic purposes, e.g., ovary and uterus evaluation, ovulation observation and development of corpus luteum, and oocyte recovery [1][2][3]. An increasing interest in non-surgical methods of oocyte recovery, as well as recovery and transfer of embryos for research purposes and practical implementation can be seen [4]. This results from the intention to maximize the application of the genetic potential of the animals on the basis of modern biotechnological programs: estrus synchronization, superovulation, oocyte recovery, in vitro maturation and fertilization, cryopreservation, and embryo transfer [5][6][7].…”