i had a heifer starting making a bag in nov.(3 months early) and not due till feb 4th. my father-in-law said she will never go to feb. i knew she had not been around a bull that early, i saw her get get bred. ithought of how it possibly could have happened. she calved feb. 5th i was right. she had a huge udder when she got close. she would not breed back, came in every 21 days for the whole breeding season.
Those girls are four months preg, but I know I've seen udders at three months before.
On the other hand, while visibly pregnant (dropped udder) I had one this year calved with no colostrum, one last year took three days after calving to come into milk - both with full term calves. Both heifers have been culled since.
Two weeks, maybe ten days, before is about the latest they start laying down colostrum... not sure when the earliest is. Eight weeks possibly.
119 in the bottom photo is about 3 weeks pre-calving and had the biggest udder of the group: http://cowcalfandvet.blogspot.com/2007/ ... ifers.html
dun as you know alot of heifers will make a false bag at 5 or 6 months bred.an then the bag will go down.but most heifers start bagging at 7.5 or 8 months bred.some may bagg longer an some less.its all just a wait watch an see game.
What breed? from what I've seen, in general, dairy heifers tend to bag up months before calving, beef heifers tend to start closer to the due date. Jerseys seem to be the worst in my limited experience with them; I've seen open Jersey heifers that were they a Holstein, I would have called them 7-8 months bred by their udder.
I think the earliest I've had was one AI-bred Holstein heifer that started bagging up around 4-4.5 months bred, looked like she was 7+ months.