A P1 cow is usually still nursing a growing calf isn't she? For mine that would be July Aug and Sept. September can be tough with slowing grass big calf still on the cow and growing a calf inside entering P2.

I find late September (still P1) can be a tough time to keep them fed but not bring out the hay yet unless absolutely necessary.

I had some trouble with calving when I had a couple bred heifers grazing corn a couple months for processing then I changed my mind and decided to let them calve.  A big mistake. Huge calves. I hate having to shoot my cattle. 

Be careful with the corn gluten on bred heifers especially.

Jim at Dawn