The Fetal Sexing Study printed below was conducted on June 1, 2000 at the University of Kentucky College of Agriculture, Animal Sciences, 907 W.P. Garrigus Building, Lexington, KY 40546-0216 by Les Anderson, Assistant Professor, and Dr. Bill Silvia

Research Report : Fetal Sexing Study

Objective

The objective of this experiment was to compare the use of transrectal ultrasonography and the Ovatec in determining fetal sex in beef cows.

Materials and Methods

Pospartum crossbred beef cows (n=107) ranging from 60 to 90 days of gestation were used in this experiment. Fetal sex was determined by two different methods in each cow. First cows were subjected to transrectal ultrasonograhpy (Sonovet 600, 7.5 MHz linear array transducer) and fetal sex was determined by visualization of location of the genital tubercle. The genital tubercle appeared as either two (vagina) or three (scrotum-penis) dense white lines either on the doral midline (male) or the subsacral posterior extreme (female) of the fetus. A single highly experienced technician performed each transrectal examination. The accuracy of the technician has been previously reported to exceed 95%.

After fetal sexing by ultrasonography, cows were mingled and fetal sex was determined using the Ovatec. After disinfection and rinsing, the vulva was cleaned and the probe was inserted in the anterior vagina. The cervix was stimulated by manual manipulation of the probe until the reading stabilized on the Ovatec device. Readings of approximately 80 were classified as male, which readings near 100 were considered female. Male readings ranged from 78-83 while female readings ranged from 96-104. Five cows exhibited readings intermediate to those classified as either male or female (88-93). The fetus in three of these cows were classified as male while the fetus in two of the cows were considered female.

Fetal sex was verified at calving. The data were analyzed using Chi Square analysis.

Results

Fetal sex was correctly determined in 106 of 107 cows using transrectal ultrasonography and in 103 of 107 cows using the Ovatec. All four misdiagnosed cows using the Ovatec had intermediate readings (3 males, 1 female). No difference (p>.10) was observed between methods for accuracy of fetal sex determination.

Conclusions

Fetal sex was accurately determined using both methods.

PLEASE NOTE:

Heritage Genetics, LLC. recommends using the following ranges of numbers for determining fetal sex in horses:

Colts - 149 or lower; 210 - 249

Filly - 250 or higher; 150 - 209