I am certainly not a cattle nutrition expert but from what I have seen I would make the cows' primary feed to be the mediocre hay all along. Cows are ruminants first and foremost. Then maybe supplement with a SMALL amount of corn or ddg's. Or mayvbe no corn/ddg's at all.

A tub of Mineralyx seems like it will also solve a lot of calving problems. From what I read, even a little bit of trace elements such as copper are important to successful calving. Hay and Mineralyx has certainly worked well for me for several seasons now. Although a calving ease bull and some easy cows may help a lot too.

What sort of condition (BCS) are the cows in?

Jim at Dawn