winter weaning

This from Dove Mountain Cross Farm:

We are currently milking out around a gallon and a half with calf sharing. We were planning on starting to wean after the holidays however I stopped in a farm store just yesterday and the owner was telling me it was a bad idea to do that in January.  So kinda got me wondering if I  should do that or not.  Any advice you could offer about this topic would be great also. 

How old is the calf you want to wean?  You'll want to wean when the calf can go onto some fairly high-quality forage.  Milk helps their rumens develop, too, so even a little milk helps.  You don't have to do a 12/12 hour share; you can give a calf half an hour a day with his mama, just to finish her out after milking, and that will make a difference.  You have to have the right infrastructure for that, though! 

We had to wean a calf early this year, and he's getting a small bottle 2x/day - it's not so much how much milk he's getting, but that he's getting it.  Think 'lactic fermentation': you don't have to add a lot of whey to a countertop pickle crock to jump-start the fermentation, a little will do.