2007 Heifer Calves January-April Calving (mostly) ~ September Photos ~ Our cows are bred in the spring to calve in our barn during the winter. Come spring, our dams have another flush of milk on the new grass, and their calves are ready to utilize the pasture season most efficiently. We try to bring late-calving cows into our timetable, although we love seeing them like this in warm, dry weather!