As in past months, I continue to talk to producers who will run out of hay before the grass greens in the spring. I always end each conversation with the statement that in a year with reduced forage, we need a mild winter. As I am writing this article it is 12° F outside and we are expecting a high today of 43.
With the beginning of cold weather, I wanted to look at some issues concerning the relationship between temperatures and feeding demands of brood cows. I would suggest that you closely monitor your cattle this winter. When the weather is cold and wet, cows need extra feed to just keep warm.
A cow needs to eat more roughage in cold weather to give her the calories for heat energy. If she doesn’t have enough roughage, the pounds will melt off of her as she robs body fat to keep warm. High quality feeds are not as efficient as roughage in producing long term heat because cows will readily gobble up the feed and stand around shivering.
If a cow has a good winter hair coat, she will do fine in dry weather until temperatures drop below 32°. With a wet hair coat due to rain and snow, this critical temperature can rise to as high as 59°. At these points, she will require an increase in feed intake to produce the body heat and stay above her lower critical temperature level. Lower critical temperature is defined as the lower limit of cattle comfort during cold weather.
When cows drop below this level, an increase in feed is required to maintain the cows’ current body status. When figuring lower critical temperature, you must also take into account the fact that wind and moisture makes effective temperature lower than thermometer temperature. You must always figure the wind-chill factor when arriving at amount of degrees below a cow’s critical temperature point. Critical temperature for any cow or calf will vary according to hair coat, moisture, age, size, amount of body fat, length of exposure, and wind. Cold stress is also less severe if the storm is brief, compared with the chill and stress of continuous bad weather.
Critical Temperature for Beef Cows
Coat Description Critical Temperature (F)
Summer Coat or wet 59 Degrees
Fall Coat 45 Degrees
Winter Coat 32 Degrees
Heavy Winter Coat 18 Degrees
A rule of thumb to compensate for cold is to increase the amount of feed (energy source) by one percent for each two degrees of cold stress. For thin cows, cows with poor hair coats or a wet hair coat figure a 1 percent increase for each degree of temperature drop. Example A: A cow that is wet will require 9% more feed at 50 degrees than that same cow at 59 degrees. Example B: A cow exposed to a wind chill temperature of 28 degrees on a dry day will require 4% more feed than the same cow at 32 degrees.
I hope that each of you had a Merry Christmas and look forward to a new year with the promise of good prices and prosperous crops.
Jimmy Hughes is AFC’s animal nutritionist.