When I was doing my daily cattle move this evening, I noticed my 11 month old Ayrshire heifer trying to ride a couple of the steers. This sounded like what I had read about heat behavior so I checked and she does have a bit of clear mucus leaking from her vagina. I believe this confirms that she is in heat. Am I right? Is there another explanation? I understand that you should breed a dairy cow at around 15 months so they calve near their second birthday, but I don't remember reading much about when they begin to have heat. Is she coming into heat too early? If it matters, the weight tape says she is 500 pounds.