Effect of dose and administration frequency of estradiol benzoate on estrogen plasma concentration in non-cyclic embryo recipient mares

• Grant number: 14/08207-6
• Support Opportunities: Scholarships abroad - Research Internship - Doctorate
• Start date: September 01, 2014
• End date: December 20, 2014
• Field of knowledge: Agronomical Sciences - Veterinary Medicine - Animal Reproduction
• Principal Investigator: Cezinande de Meira
• Grantee: Elisa Sant'Anna Monteiro da Silva
• Supervisor: Janet F. Roser
• Host Institution: Faculdade de Medicina Veterinária e Zootecnia (FMVZ). Universidade Estadual Paulista (UNESP). Campus de Botucatu. Botucatu , SP, Brazil
• Institution abroad: University of California, Davis (UC Davis), United States
• Associated to the scholarship: 12/00298-7 - Qualitative and quantitative evaluation of estrogen and progesterone receptors in non-cyclic mares treated with estradiol benzoate and Altrenogest, BP.DR

Abstract

Estrogens and progestins treatments are usually applied in equine embryo transfer programs in order to establish pregnancy in non-cyclic mares. Although standardized protocols for exogenous progestins are already described, there are no studies determining the dose and administration frequency of benzoate estradiol that, in addition to causing endometrial edema, produce similar estrogen hormone profile to that found in cyclic mares during estrous. The present study aims to evaluate the influence of different doses and administration frequencies of estradiol benzoate on estrogen plasma concentrations in non-cyclic embryo recipient mares. Twenty one anestrous mares will be distributed into three groups (n=7 mares/group): 2.5mg EB + LA P4, in which a single 2.5mg dose of estradiol benzoate (EB) followed by 1500mg of long action progesterone (LA P4) will be administered; 5mg EB + LA P4, in which decreasing doses of 5 mg of EB on two consecutive days followed by 1500mg of LA P4 will be administered; and 10mg EB + LA P4, in which decreasing doses of 10 mg of EB on three consecutive days followed by 1500mg of LA P4 will be given. These mares will be reevaluated during the ovulatory phase and seven of them will be part of the non-treated Control group. During the hormonal treatments in non-cyclic mares and corresponding cyclic phase (estrous and early diestrous) in the Control group, B-mode ultrasonography will be performed to evaluate endometrial edema and blood samples will be collected to measure estradiol and progesterone daily. The knowledge of an exogenous estrogen protocol that is more compatible with endogenous estrogen concentrations found in cyclic mares will allow an optimization of the hormone use in non-cyclic embryo recipient mares. (AU)

Scientific publications

(References retrieved automatically from Web of Science and SciELO through information on FAPESP grants and their corresponding numbers as mentioned in the publications by the authors)

SILVA, E. S. M.; ROSER, J. F.; GOMES, A. R. C.; FRITSCH, S. C.; PANTOJA, J. C. F.; OLIVEIRA-FILHO, J. P.; MEIRA, C.. Comparison of different regimens of estradiol benzoate treatments followed by long-acting progesterone to prepare noncycling mares as embryo recipients. Theriogenology, v. 86, n. 7, p. 1749-1756, OCT 15 2016. (14/08207-6)