) Newly developed vaginal probe to detect freemartin heifers and/or determine if heifers born co-twin to a bull have a normal reproductive tract. The crucial probe end length is 7 cm. Research has shown that no freemartin calf has a vaginal length longer than 7 cm. The digital end of the narrower center section is 14 cm from the tip. Over 95% of heifers born co-twin to a bull and with a normal reproductive tract have a vaginal length of 14 cm or more. If vaginal length is 7-14 cm, a chromosome testing should be done to confirm if it’s a freemartin. It is designed to be used on heifers 30 days of age or less.