Can depend on your climate how well calves do over the winter. A neighbor who has a cattle scale, for a number of years calved out in Feb. which can have some fairly cold temperatures, not uncommon to hit minus 30 F*
He decided to try out March calvings for a bit and discouvered at sale time there was almost no difference in the weight between
Feb Calves and March calves. He figured that the Feb calves burned alot of their energy just trying to stay warm, where the March calves, put more energy towards growing.
Other people say March calves have a higher scours rate due to mud during break up.
so take your pick.personally I prefer March, checking animals at minus 30 during the night and having to warm critters that get chilled isn't fun.....