I read somewhere that a calf's maximum nutrition needs from the cow and cow's maximum nutrition requirement for lactation occurs about 60 days post calving.

This article also went on to say that therefore, unless you are supplementing the cow somehow, in any given location you should time your calving target date for 60 days prior to your peak grass period.

In S WI this peak grass is probably early June so by this logic my target calving date is early April. Splitting the 21 day cow cycle, earliest calving would then ideally be April 1st or so. By my gestation chart, my bull-in date is then June 20th or somewhere thereabouts, at least by this peak grass article logic.  Because I want to harvest most of mine off of grazing corn in late April next year I may fudge on this a bit and am looking at putting my bull in on June 15th. fwiw.

Jim at Dawn