kdhansen,
We do have both spring and fall calving seasons... and will, on occasion, roll a yearling heifer that didn't breed with her contemporaries at 14-15 months to the next season, to breed at 18 months. If she doesn't stick then, she's taking a ride to town.
Likewise, we'll also occasionally let a good 1st-calf heifer that doesn't breed back on her inaugural outing roll to the next season, especially if she's doing a great job with her calf, and just 'milked down' a bit too much.
Is your 18 month basically the date to try to keep her calving age from being past the ~27 month, or at that point (2nd chance), that is not a concern, what will be will be?
Some will say that we're 'making excuses' for too many... but... I like 'em, I'm breeding what I want, and I'm not dependent upon income from them to survive.
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