Hopefully, nothing. Most of the time, an experienced cow will do it all on her own.
But...I've got two in the tackroom right now, born today in 2 ft of snow - and temps due to go below 0 tonight. One born after noon had melted through the snow, down to green grass - with her feet sticking up in the air; was essentially cast and had worn itself out trying to get up.
Towels for drying, blankets for the floor and to cover the calf, an old sweatshirt or sweater. A nursing bottle and an esophageal tube feeder(I prefer the flexible plastic probe types, rather than rigid), a top quality colostrum replacer(not supplement), in the event that the calf can't/won't nurse, or you can't get the cow in to milk her out.
I wouldn't worry much about 'injections' right off the bat...get the calf up and going first, then deal with any other issues.
Tomorrow's chore - get the two cows in and pair 'em back up with their calves.
I have 5 more due to calve any minute now(due yesterday); hope they'll hold off 'til daylight - I'm out of colostrum replacer and frozen colostrum 'til I can hit TSC in the morning &/or milk out one of these two cows.
