Just use vinegar
HOn those cold calves ears right away.. Front, Back and Inside the ear, as they're born etc..
Vinegar keeps those ears from freezing if that seems to be an issue for those calfing in the real cold temps.
anyway , non froze ears are generally saved from a $5cwt discount down the road when selling cattle.
irregardless...buffalo , deer and antelope tend to calf in May and June...all native to and evolved in NA.