You don't want to see ribs sticking out on the heifers. They really need to be in good condition. If necessary, they should be separated from the other cows and eating well.
It's a good year for moving sheep into barns for lambing. Remember to keep the sheep in clean, dry pens, free from drafts. There needs to be good ventilation to avoid pneumonia. We've just been spoiled in recent years by fairly easy winters.