Comparison of Two-Dimensional Ultrasound and Three-Dimensional Ultrasound in Fetal Sexing of Cattle

Fetal sexing using three-dimensional ultrasound is a relatively new technique that may improve the ability to determine gender of cattle fetuses. Fetal sexing with real-time B-mode two-dimensional ultrasound was performed transrectally in twenty-five Holstein heifers between days 55 to 65 of gestation. A gender diagnosis, if available, was given immedicately after two-dimensional ultrasound scanning. Male designation was given to those fetuses whose genital tubercle was near the umbilical cord, female designation was given to those fetuses whose genital tubercle was near the tail, and no diagnosis was given in circumstances where visualization of the genital tubercle could not be determined. Three-dimensional images were acquired and saved for later gender determination. Viewing of the three-dimensional images was performed four weeks later with no knowledge of prior two-dimensional ultrasound diagnosis. A diagnosis of male, female, or no diagnosis was given using three-dimensional ultrasound utilizing the same gender diagnosis criteria for two-dimensional ultrasound. Statistical analysis of gender diagnoses available with two- or three-dimensional ultrasound revealed a significant difference. Two-dimensional ultrasound allowed gender diagnosis in 76% (19/25) of the sample while three-dimensional ultrasound allowed gender diagnosis in 48% (12/25) of the sample. Neither ultrasound system permitted gender diagnosis 12% (3/25) of the time. There were 10 cases in which only two-dimensional ultrasound provided a gender diagnosis and 3 cases where gender diagnosis was available with just three-dimensional ulrasound. In this study, three-dimensional ultrasound did not improve the ability to diagnose gender of bovine fetuses when compared to two-dimensional ultrasound