Correlation of maternal concentrations of plasma testosterone with fetal sex in horses

Eduarda Maciel Busato,Luiz Ernandes Kozicki,Peterson Triches Dornbusch,Vanete Thomaz Soccol,Felipe Augusto Beckert Marcondes,Romildo Romualdo Weiss,Tácia Gomes Bergstein‐Galan ,Ana Cláudia Machinski Rangel De Abreu

doi:10.1590/0103-8478cr20200237

Abstract

ABSTRACT: The objectives of this study were to evaluate the correlation of fetal sex and plasma testosterone concentrations between the 5th and 8th months of pregnancy in mares and to verify the applicability of this test to predict fetal sex. Blood samples were collected from 21 mares at 30-day intervals of between 150 and 240 days of pregnancy. Plasma testosterone was determined by radioimmunoassay and the sex of the foals confirmed at birth. The levels of maternal testosterone were higher in mares carrying female fetuses at months 5 and 8 (P < 0.05). Limit values were determined by analyzing the receiver operating characteristic (ROC) estimates: 35.5 pg/mL and 40 pg/mL for the 5th and 8th month, respectively. For the mares with plasma testosterone values equal to or above the threshold, gestation of female foals was predicted, and for those with plasma testosterone below the threshold values pregnancy of male foals was predicted. In the 5th month, the predictive values for male and female fetuses were 70% and 88.9%, respectively; the detection rates were 87.5% and 72.7%, and the total accuracy of the examination was 78.9%. In the 8th month, the predictive values for male and female fetuses were 80% and 90%, respectively; the detection rates were 88.9% and 81.8%, and the total accuracy of the examination was 85%. It was concluded that there was a correlation between fetal sex and plasma testosterone concentrations in pregnant mares. Prediction of fetal sex based on plasma concentrations of maternal testosterone can be performed in months 5 and 8 with 78.9% and 85% accuracy, respectively.

Highlights

Prenatal diagnosis of fetal sex is routinely performed in human medicine; whereas, in veterinary medicine is primarily employed in cattle and horses
There was a statistically significant difference between plasma testosterone levels in pregnant mares carrying male fetuses compared to that of mares carrying female fetuses during the 5th and 8th months of pregnancy, and higher values were reported in mares carrying female fetuses (Figure 2)
Threshold values for maternal testosterone levels used to predict fetal sex were established by analyzing the receiver operating characteristic (ROC) curves for months 5 and 8 of pregnancy (Figure 4)

Summary

Introduction

Prenatal diagnosis of fetal sex (fetal sexing) is routinely performed in human medicine; whereas, in veterinary medicine is primarily employed in cattle and horses. Interest in fetal sexing varies according to the species and/or breed in question. V.51, n.2, wild species kept in captivity, fetal sexing can be used as a tool for management, which is often different between males and females (DUER et al, 2002). The interest for foals of a particular sex varies according to breed, activity and preference of the owner. There is a preference for females (PASHEN et al, 1993; PANARACE et al, 2014), while in racehorses, males are usually preferred (CHEZUM & WIMMER, 1997). Whether or not to put pregnant mares to auctions or an animal’s market value or insurance value may be directly affected by the sex of the animal (MCGLADDERY, 2011; AURICH & SCHNEIDER, 2014)

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Results