Embryo and cow factors affecting pregnancy per embryo transfer for multiple-service, lactating Holstein recipients

Abstract

The objective was to determine whether pregnancy success after embryo transfer (ET) during heat stress in multi-service Holstein cows depends upon characteristics of the embryo or recipient. Female embryos produced in vitro were cultured with either 0.0 (control) or 1.8 mM choline chloride and transferred fresh. Fresh embryos of undetermined breed and frozen Holstein embryos were used when experimental embryos were insufficient. Embryos were transferred 8 d after the last GnRH injection of an ovulation synchronization program. Embryo type [frozen vs. fresh, choline vs. control, unknown breed vs. (control + choline)] and characteristics of recipients (average of 190 d in milk at transfer) were evaluated. Pregnancy per ET was lower for cows receiving frozen embryos (7.0%; 3/43) than for cows receiving fresh embryos (26.7%; 32/120) but there were no differences between various types of fresh embryo. Pregnancy per ET was lower for cows diagnosed with metritis in the early postpartum period (7.1%; 2/28) than for cows without metritis (24.4%; 33/135). In conclusion, the use of frozen/thawed embryos produced in vitro and recipients which had metritis in the early postpartum period reduced the success of ET in multiple-service Holstein cows.

The incompletely fulfilled promise of embryo transfer in cattle—why aren’t pregnancy rates greater and what can we do about it?

“…While overall pregnancy rates were higher when a MOET embryo was transferred, the magnitude of the reduction in P/ET caused by cryopreservation was either similar for embryos of both types ( Numabe et al, 2000 ) or higher for MOET embryos than IVP embryos ( Ferraz et al, 2016 ). The particular culture conditions used to produce embryos in vitro can affect the ability of IVP embryos to survive cryopreservation ( Block et al, 2009 ; Paschoal et al, 2014 ), and some systems used for the production of IVP embryos do result in blastocysts with poor survivability to cryopreservation ( Vieira et al, 2007 ; Estrada-Cortés et al, 2019 ).…”

“…Further evidence for poor uterine receptivity as a cause of infertility was the finding that 14 of 37 (32.4%) recipients receiving five embryos failed to become pregnant to any embryo ( Martins et al, 2018a ). Examples of cow factors associated with poor P/ET are low body condition score ( Mapletoft et al, 1986 ; Wallace et al 2011 ), poor weight gain ( Fernandes et al, 2016 ), lactation or parity in dairy cattle ( Dochi et al, 1998 ; Hasler, 2001 ; Ferraz et al, 2016 ), temperament ( Kasimanickam et al, 2018 , 2019 ), and periparturient or postpartum disease ( Ferraz et al, 2016 ; Ribeiro et al, 2016 ; Barbosa et al, 2018 ; Estrada-Cortés et al, 2019 ).…”

Lineage Differentiation Markers as a Proxy for Embryo Viability in Farm Ungulates

“…In order to improve in vitro embryo production techniques, it is essential to assess embryo quality, i.e., the odds of post-transfer survival, to determine which modifications of current protocols are beneficial for subsequent embryo survival. Arguably, the best embryo quality assessment would be the analysis of embryo development following embryo transfer, but this test holds two major drawbacks ( 1 ) it is expensive, time-consuming and requires the use of experimental animals and ( 2 ) it is inherently bound to intrinsic variabilities in uterine receptivity between females ( 112 , 113 ). Morphological evaluation ( 114 ), widely used both in humans and farm animals to select embryos before transfer due to its non-invasive nature, is certainly useful, as pregnancy rates are higher when better-quality grade embryos are transferred ( 115 – 118 ).…”

Inflammatory diseases in dairy cows: Risk factors and associations with pregnancy after embryo transfer

“…Inflammatory diseases affect pregnancy in dairy cattle receiving AI, although the underlying mechanisms are complex and multifaceted. Less is known about the impact of inflammatory diseases on maintenance of pregnancy following ET (Ribeiro et al, 2016;Barbosa et al, 2018;Estrada-Cortés et al, 2019). Segregating diseases into those that affect the uterus or other tissues may provide insight on potential underlying mechanisms of inflammation-associated subfertility that are directly linked to the reproductive tract or with systemic effects of inflammation.…”