DETERMINAÇÃO ULTRASSONOGRÁFICA DO SEXO FETAL EM ÉGUAS DA RAÇA CRIOULA ENTRE O 59° E O 126° DIAS DE GESTAÇÃO, EM CONDIÇÕES DE CAMPO.

The aim of this study was to compare the efficacy of fetal sexing by genital tubercle with that based on the evaluation of fetal gonads performed in field conditions in horses. A total of 27 Crioulo breed mares were used, which were submitted to the referred examinations of fetal sexing by transrectal ultrasonography at two different times. A single technique evaluation was performed on each animal and the sex of the foals was confirmed at birth. The sexing by the identification and positioning of the genital tubercle occurred between 59 and 65 days of gestation, resulting in a possible diagnosis rate of 51.9% (14/27) and accuracy of 85.7% (12/14). The sexing based on the evaluation of fetal gonads was performed between 117 and 126 days of gestation, with the possible diagnosis rate being 88.9% (24/27) and the accuracy 83.3% (20/24). The rate of possible diagnoses for each technique and accuracy of the tests during the two diagnostic windows were compared statistically using the chi-square test, with a significance level determined for P <0.05. The accuracy of both techniques did not present difference (P = 0.85), however, the possible diagnosis rate was higher by the technique based on the fetal gonads (P = 0.003). It was concluded that, under field conditions (not optimized), fetal sexing through the evaluation of fetal gonads presented better efficacy, with the main advantage being the higher rate of possible diagnoses. [ABSTRACT FROM AUTHOR]