How can we improve embryo production and pregnancy outcomes of Holstein embryos produced in vitro? (12 years of practical results at a California dairy farm)

Abstract

Genomic evaluations have revolutionized dairy cattle breeding, and the demand for embryos produced from very young heifers with high genetic merit has increased over time. The combination of low oocyte recovery, young age of donors, and milk production status can make the in vitro embryo production (IVP) of Holstein cattle incredibly challenging. Several factors need to be coordinated to obtain a live calf from an IVP embryo, but the quality of the oocyte at the start of the process is one of the key factors. Aspects related to oocyte quality, laboratory quality control, embryo quality and recipient selection are addressed here, based on the measures that the RuAnn Genetics Laboratory (Riverdale, California, USA) adopted in the last 12 years, with the goal of improving production of live, healthy calves from Holstein embryos. Follicular wave synchronization and stimulation with follicular stimulating hormone (FSH) is necessary to improve oocyte quality and consequently embryo production. Laboratory quality control and the use of high-quality supplies are essential to reduce variability in production and facilitate identification of other factors that might interfere with embryo production. High pregnancy rates can be achieved with good quality embryos selected at optimal time and stage of development, transferred by an experienced embryo transfer (ET) technician, to well managed recipients 7 or 8 days after estrus. Attention to detail at every step of the process is crucial to success.

Does using microfluidic sperm sorting chips in bovine IVEP affect blastocyst development?

“…Anbari et al (2021), Guler et al (2021), and Mirsanei et al (2022) reported that embryo quality increased after sperm selection with a microfluidic sperm sorting device before ICSI application. Many factors affect embryo quality in cattle (Demetrio et al, 2020; Lonergan et al, 2001; Sartori et al, 2010), and possible effects of spermatozoa processing and selection methodologies are among them (Anbari et al, 2021; Henkel & Schill, 2003). Because depending on the method used, it is stated that there is a negative relationship between DNA fragmentation that occurs during spermatozoa separation and embryo quality (Avendañ & Oehninger, 2011; Nagata et al, 2018).…”

Transvaginal ultrasound‐guided oocyte retrieval in cattle: State‐of‐the‐art and its impact on the in vitro fertilization embryo production outcome

“…Topic #1: The synchronization of the follicular wave emergence prior to OPU increased the number of viable oocytes recovered and transferable blastocysts Bos taurus breeds (Bordignon et al, 1997, Fernandes et al, 2014, Hendriksen et al, 2004, Hidaka et al, 2018, Ongaratto et al, 2015 ( Gimenes et al, 2015) Bos indicus breeds (Cavalieri et al, 2018, Fernandes et al, 2014) (Gimenes et al, 2015, Ongaratto et al, 2015, Ramos et al, 2010 Topic #2: Follicular superstimulation by FSH or FSH/LH increase the number and quality of retrieved oocytes and viable embryos produced per OPU Bos taurus breeds (Blondin et al, 2002, Chaubal et al, 2007, De Roover et al, 2008, Demetrio et al, 2020, Fernandes et al, 2014, Vieira et al, 2014) (da Silva et al, 2017, Oliveira et al, 2016 Bos indicus breeds (Fernandes et al, 2014) (Baruselli et al, 2016, Monteiro et al, 2010, Ongaratto et al, 2015 F I G U R E 8 Relationship between the vacuum pressure (mmHg) and the amount of water collected with different sizes of needles (18G, 19G and 21G) (Bols et al, 1996) demand for the use of younger animals to shorten the generational interval (Loi et al, 2016). Today, prepubertal calves are highly relevant within the OPU-IVP commercial service.…”

“…This is a determining factor for the donor embryo production potential. Donor selection by AFC before starting an OPU program is a highly recommended practice (De Roover et al, 1997; De Roover et al 2005a; Demetrio et al, 2020). The count of antral follicles >3 mm in both ovaries ≤15 is considered low, 16–24 medium and ≥25 follicles being a high ovarian follicle population for Bos taurus females (Ireland et al, 2008).…”

“…The coasting or FSH deficiency period simulates an in vivo initial dominance phase, this induces a pre‐ovulatory type of follicle environment, which triggers or promotes cytoplasmic maturation before the in vitro conventional maturation period begins. Currently, protocols are being developed to simplify the FSH administration in a single injection (Moraes et al, 2019; Ongaratto et al, 2020; Vieira et al, 2016) and reducing the coasting time period between 16–20 h after the last FSH injection in heifers and 26–30 h in cows (Demetrio et al, 2020).…”