I went down to feed her and noticed that she has lost the hair off of the end of her tail. She had a calf about a month ago and both are doing really well. She doesn't act sick and is eating and drinking good. Is this something to be worried about? Does anyone know why it happened? Any advice is appreciated Thanks!
Probably swatting at flies while hiding in shade of brush or trees along a barbwire fence. Sometimes they get the switch end stuck in fence and it tears away when they walk away.
If there is no blood - no worries.
If she tore the end of tail off and there is a bloody stump which is dripping causing a steady stream of blood loss, simply catch and restrain cow, slide a little green cheerio size castrating rubberband about an inch above wound and release it there to act as a tourniquet. This will stop the bleeding, eventually the tail end will fall away and she will have a shorter tail - but she won't become sick from the loss of blood.
Another way I've seen cows lose the end of their tail is from Predatory attacks. A Wolf or a pack of Coyotes can pull the tail off a cow trying to bring them down. If there are fang marks in the lower rear legs on a cow or in the haunches of a calf then they probably fended off Predators and survived.