Expression of estrus as a relevant factor in fixed-time embryo transfer programs using estradiol/progesterone-based protocols in cattle.

Gabriel A Bó,Andrés Cedeño

doi:10.21451/1984-3143-ar2018-0060

Abstract

The main objective of implementing embryo transfer in beef operations is to accelerate the rate of genetic progress in the herd. Among the main factors that affect the use of these technologies are related to nutrition, management and estrus synchronization. As a result of research conducted over the last 20 years, recipient utilization has increased by applying protocols that synchronize ovulation and allow for embryo transfer without the need for estrus detection, usually referred to as fixed-time embryo transfer (FTET). Although these protocols have performed adequately for several years, recent attention has been directed to the effect of estrus expression and estradiol concentrations during growth of the preovulatory follicle on embryo growth and pregnancy. The experiments reviewed herein demonstrate that estrus expression is associated positively with high pregnancy rates and reduced pregnancy losses in recipients receiving in vitro-produced and in vivo -derived frozen/thawed bovine embryos.

Highlights

The main objective of an embryo transfer program is to increase the genetic value of the offspring produced in a given herd
The protocol for FTAI was named J-Synch. This treatment protocol has resulted in higher per AI (P/AI) rates in beef heifers compared to the conventional protocol in which the P4-device is removed on day 7 and estradiol cypionate (ECP) is given at that time (Bó et al, 2016)
Two other studies were performed in Argentina to confirm that the expression of estrus had a positive effect on P/fixed-time embryo transfer (FTET) and maintenance of pregnancy in recipients treated with estradiol/P4-based protocols

Summary

Introduction

The main objective of an embryo transfer program is to increase the genetic value of the offspring produced in a given herd. Ovulation is induced by the administration of 0.5 or 1 mg of estradiol cypionate (ECP) at the time of P4-device removal and all recipients with a CL receive an embryo 9 days later (i.e., 7 days after the expected time of estrus; Baruselli et al 2010, 2011; Bó et al 2012a, b). This treatment protocol has resulted in higher P/AI rates in beef heifers compared to the conventional protocol in which the P4-device is removed on day 7 and ECP is given at that time (Bó et al, 2016).

Results

Conclusion