Newborn cattle may be difficult to sex because their "parts" are smaller. If you cannot tell from just looking, you may have to get up close and personal to determine if the new baby is a bull or heifer. Boys are usually easier to sex than the girls are. Like any other mammal, males have testes and a penis while females have a vaginal area. A quick bit of cattle sex terminology -- cows are female cattle or bovine, heifers are female calves, steers are neutered male cattle and bulls are intact cattle or bovine.
Lift the tail of the calf. Look under the tail for the male or female parts. The testes or vagina will be located just in front of the anal opening.
Feel under the tail if you cannot see the genitals. On young calves, you may not be able to easily see the male or female parts. In these cases, you can feel for them.
View the calf from the side and look under the belly of the calf. The male's penis will be set between the back legs and the stomach -- which may still have the umbilical cord attached in newborn calves.