03863naa a2200253 a 450000100080000000500110000800800410001902200140006002400390007410000140011324501070012726000090023450011040024352019350134765300080328265300140329065300180330465300090332265300400333165300560337165300410342770000170346877301240348510643862023-12-05       2023    bl uuuu     u00u1 u    #d  a1806-96147 a10.1590/1984-3143-AR2023-00672DOI1 aBÓ, G.A.  aProhibition of hormones in animal reproductionbwhat to expect and what to do?.h[electronic resource]  c2023  aArticle history: Received May 15, 2023; Accepted: July 18, 2023. -- Financial support: GAB received funding for this research from Fondo Nacional de Ciencia y Tecnología (FONCYT PICT 2017-4550), Instituto de Investigación Universidad Nacional de Villa María (UNVM) and Instituto de Reproducción Animal de Córdoba (IRAC). AM is a researcher of the Sistema Nacional de Investigadores (SNI) of Uruguay, and received financial support from Agencia Nacional de Investigación e Innovación (ANII, PR_FMV_3_2016_1_125451), from Fundación IRAUy, and from Instituto Nacional de Investigación Agropecuaria (INIA, Uruguay). -- Document type: Article Gold Open Access, Green Open Access. -- Correspondence:   Bó, G.A.; Instituto de Reproducción Animal Córdoba, Córdoba, Argentina; email: gabrielbo62@gmail.com  --  License: This is an Open Access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited. (https://creativecommons.org/licenses/by/4.0/ )  aAs our understanding of ovarian function in cattle has improved, our ability to control it has also increased. The development of Fixed-Time Artificial Insemination (FTAI) protocols at the end of the 20th century has increased exponentially the number of animals inseminated over the last 20 years. The main reasons for this growth were the possibility of obtaining acceptable pregnancy rates without heat detection and, above all, the induction of cyclicity in suckled cows in postpartum anestrus and prepubertal heifers at the beginning of the breeding season. Most FTAI treatments in South America have been based on the use of progesterone (P4) releasing devices and estradiol to synchronize both follicular wave emergence and ovulation, with pregnancy rates ranging from 40 to 60%. These protocols are implemented on a regular basis, allowing producers access to high-quality genetics, and increasing the overall pregnancy rates during the breeding season. In addition, it provided the professionals involved in these programs with a new source of income and the diversification of their practices into activities other than their usual clinical work. Many of these practices are now apparently at risk from restrictions on the use of estradiol by the European Union (EU) and other countries. However, the development of alternative protocols based on GnRH, with P4 devices and eCG and other new products that are not in the market yet will allow us to adapt to the new times that are coming. Logically, the challenge has already been raised and we must learn to use alternative protocols to try to continue increasing the use of this technology in beef and dairy herds. The objective of the present review is to describe the main aspects of banning estradiol in livestock production, the negative impacts on reproductive efficiency, and to present some alternative FTAI protocols for dairy and beef cattle. © The Author(s).  aECG  aEstradiol  aFixed-time AI  aGnRH  aPartnership for the goals - Goal 17  aPLATAFORMA DE INVESTIGACIÓN EN SALUD ANIMAL - INIA  aSustainable Development Goals (SDGs)1 aMENCHACA, A.  tAnimal Reproduction, 2023, Volume 20, Issue 2, e20230067. https://doi.org/10.1590/1984-3143-AR2023-0067 -- OPEN ACCESS.