Use of long-acting progesterone to acyclic embryo recipient mares

Gabriel Maksoud Greco,Fernando José Rohen De Queiroz,Maria Pia Dos Santos Cunha,Fábio Luis Gonçalves Burlamaqui,Aline Emerim Pinna,Felipe Zandonadi Brandão

doi:10.1590/s1516-35982012000300019

Gabriel Maksoud Greco, Fernando José Rohen De Queiroz + Show 4 more

Open Access

https://doi.org/10.1590/s1516-35982012000300019

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Abstract

The objective of this study was to evaluate the efficiency of cyclic and acyclic progesterone-treated recipient mares in a commercial embryo transfer program. Acyclic recipients were treated with decreasing amounts of estradiol cypionate (ECP® - Pfizer Saude Animal, Sao Paulo, Brazil), followed by 1500 mg of a sustained-release progesterone injection (P4LA150® - Laboratorios B.E.T., Rio de Janeiro, Brazil). Out of all 1506 embryo recovery attempts performed, 59.36% were positive (894/1506). Pregnancy rates of cyclic and acyclic mares were, respectively, 44.12% (319/723) and 57.68% (139/241) - higher in acyclic recipients under progesterone treatment. Embryo loss was similar between groups (9.72% 31/319 vs. 11.51% - 16/139). When fertility data on acyclic mares treated with long-action progesterone were grouped in relation to the interval of the beginning of the treatment with progesterone to the embryo transfer, there was no difference in pregnancy rates at 12 days (51.28% - 20/39; 58.92% - 33/56; 60.52% - 46/76 and 58.57% - 41/70 for embryos transferred 3 (P3), 4 (P4), 5 (P5) and 6 (P6) days after the beginning of the treatment with progesterone). Groups P3, P4, P5 and P6 showed embryo loss rates of 20.00% (4/20), 12.12% (4/33), 2.17% (1/46) and 17.07% (7/41), respectively. These rates were similar in groups P3, P4 and P6. Pregnant recipients submitted to an embryo transferring procedure on P5 showed lower embryo mortality rates than on P3 and P6. P4 recipients tended to suffer higher embryo mortality rates than P5. Acyclic recipient mares under progesterone treatment can be satisfactoryly used in embryo transfer programs.

Highlights

In Brazil, equine embryo transfer has been facing growing interest since the first national studies were published (Fleury et al, 1987; Henry et al, 1987)
When fertility data on acyclic mares treated with long-action progesterone were grouped in relation to the interval of the beginning of the treatment with progesterone to the embryo transfer, there was no difference in pregnancy rates at 12 days (51.28% - 20/39; 58.92% - 33/56; 60.52% - 46/76 and 58.57% - 41/70 for embryos transferred 3 (P3), 4 (P4), 5 (P5) and 6 (P6) days after the beginning of the treatment with progesterone)
Acyclic recipient mares under progesterone treatment can be satisfactoryly used in embryo transfer programs

Summary

Introduction

In Brazil, equine embryo transfer has been facing growing interest since the first national studies were published (Fleury et al, 1987; Henry et al, 1987). Brazil is one of the main countries in number of annual successful transfers (Losinno & Alvarenga, 2006). In order to obtain satisfactory results, it is essential that progesterone act on the reproductive tract of recipient mares (Mckinnon et al, 1988a; Fleury, 2002). Progesterone is the only ovarian hormone necessary to maintain an early pregnancy in the equine species (Wilker et al, 1991; Goff, 2002). Ovariectomized or acyclic mares under hormonal treatment can be successfully used as embryo recipients (Hinrichs et al, 1985; Carnevale et al 2000; Riera et al, 2008).

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