Instead of focusing just on her bag, springing & subsequent mucus plug, watch her behavior. First calf heifers tend to separate, pace, act needy, pay way too much attention to other calves, either can't get enough cubes or not want to eat. She may get a little fired up. Watch her lay down, get up, lay down. She may look at her behind and start mooing. She knows something's going on! Look at her from behind and she won't look as heavy bred when the calf drops into position. And good luck! She may calve and mother up like a champ. But she also may do the "heifer dance" and initially not let her calf nurse. Cubes are your friend! Dump a pile and get the calf latched on while she's occupied, which will kick her mothering hormones into high gear. Or should. Safety first - always use a chute if there's any question.
