There are many considerations regarding when a rancher wants his/her cows to start calving. In the winter time, the native range just can’t supply the necessary nutrients for a cow, let alone a cow growing a calf inside her, so most ranches in the Northern Rockies feed hay through the winter months. Feed is the most expensive part of raising beef in the north, so how much a ranch has to feed has a significant impact on the bottom line.
Cows due to calve early in the year, say January or February, will need more hay in those last (and coldest) months of pregnancy, but their calves will be bigger when it’s time to go to market with them in the fall, so for some outfits it makes sense to calve early.
However, later calving (April/May) coincides better with spring green up which provides a boost in nutrients that help the mother cow support that last month of pregnancy and the coming demands for milk production. The warmer weather is also an added benefit to the calves, but it can be a bit of a crap shoot. Spring time in the Rockies can turn from balmy to blizzard in the blink of an eye, and almost nothing is harder on a new born calf than cold, wet weather. Wet weather in the 40’s (degrees) is harder on a newborn calf than a dry day in the 20’s.
Timing calving to coincide with green up is a closer approximation of how nature does things, but even though it is greening up around here, the deer, elk and antelope are still a month or two from having their young ones. The weather around here has been the usual sporadic fair; the pendulum swinging from sunny to snowy, but the snow squalls have passed quickly and the beef crop looks good.