ORIGINALLY WRITTEN STEVE TONN
Periods of extreme cold cost the cow-calf producer in dollars for extra feed or lost weight, but there are important points to remember that will help to keep those costs from going out of sight.
What’s more important, energy or protein? Cold weather increases the cow’s energy requirement, not its protein needs, which remain the same. The energy requirement depends on the degree of chill or temperature, amount of body weight that must be maintained, the amount of fleshing and winter hair coat.
Thinner cows are going to be more severely affected by adverse weather conditions than animals in average condition. It’s important that thinner spring calving cows not lose additional weight. Two or three weeks of cold stress can have a major affect on this type of cow.
If you need extra energy into cows, the question is how do I do it most economically. Do I use roughage or grain? Don’t automatically overlook grain. One pound of grain supplies as much energy as one and one half pounds of hay.
When hay is high priced and grain is cheap, then grain may be a more suitable energy source.
The protein, mineral and vitamin requirements stay the same when temperatures drop, so care should be taken to sort this out if costs are to be managed. That’s because protein supplements are normally much more expensive than feeding straight grain. The critical temperature or the temperature at which weather increases energy requirements begins at about 25 to 30 degrees F. From that temperature on down, energy needs climb.
Basically, for each degree below that critical temperature, there is a 1 percent increase in demand for total digestible nutrients if the cow is to stay warm and maintain body weight.
Although there are other considerations, a windchill index of 20 below zero will be considered the same as a thermometer temperature reading of 20 below, although the mercury may read only 10 degrees above zero.
In this case, a windchill of 20 below is from 45 to 50 degrees under the critical temperature or under the bottom of the comfort zone for the cows.
This means she will require a 45 to 50 percent increase in her energy in her ration. So a 1,000-pound cow that can get by comfortably in comfort zone temperatures with 17 to 18 pounds of hay will have to be fed 26 to 28 pounds of hay to maintain herself in the same fashion.
An increase of four or five pounds of corn, wheat, or milo will accomplish the same goal as the increase in hay.
Though most of the shelter decisions will have been made earlier in the year, it’s important that producers know that windbreaks can cut the windchill factor and save on the energy bill. A wooden fence with a one-inch open space between six-inch upright boards is more effective in reducing adverse effects of weather than is a solid fence.
The slatted fence slows down the wind but does not allow the snow to swirl over into a drift on the leeward side. Shelter belts, banks along creek beds and other structures also serve to slow the wind and therefore the windchill factor.
Heated water sources serve two important purposes-one is to assure an uninterrupted supply of water-the other is to reduce the amount of hay or grain needed in a cow’s stomach to heat up the water once it is ingested.