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Watch Cattle Nutritional Requirements in Cold Weather
USAgNet - 11/12/2008

Very cold temperatures and bitter wind chills make managing cattle nutrition critical for ranchers.

Low temperatures and wind can increase cattle nutrient requirements by 20 to 30 percent, South Dakota State University Extension Beef Specialist Cody Wright said.

"A good rule of thumb is that for every degree below 32 degrees, including wind chill, a cow's energy requirements increase by 1 percent," Wright said. "How you manage your cows between now and calving may have the single largest impact on how your cows breed back next summer."

Here are some tips:

-- Take special care with thinner cows (those with a body condition score of less than 5). They have less insulation from fat and so are more susceptible to colder temperatures.

-- Remember that maintenance energy requirements will increase as temperatures fall below "lower critical temperature." The lower critical temperature depends on hair coat, wind, wet, and body condition. The lower critical temperature for a cow in moderate condition with dry winter coat is around 30 degrees Fahrenheit.

-- Keep animals dry and sheltered from wind, if possible. If cattle have wet hair coats or it is very windy, the cattle will feel much colder and thus have increased requirements -- the lower critical temperature is increased in these situations.

"The energy requirements of wet cattle generally increase by 2 percent for every degree below 59 degrees Fahrenheit," Wright said. "It becomes imperative to practice good animal husbandry and provide bedding and shelter from the wind and precipitation if possible."

Free-choice access to forage during severe winter conditions is one simple way to help cows cope with cold stress. At extremely cold temperatures, it is unlikely that the cows will be able to consume enough forage to meet their requirements. However, heat generated during the digestive process, especially fermentation in the rumen, helps maintain core body temperatures.

Cattle will eat more when it is cold. As temperatures get very cold, increase the feeding rate above maintenance. Assuming cows are fed a diet to just meet requirements with moderate winter weather, feed 3 to 4 pounds more hay (i.e. alfalfa hay) or 2 to 3 pounds more grain to account for the increased requirements.

Cattle spend less time grazing in extreme cold so supplemental feeding may become necessary. Generally, a 1,200-pound cow can be fed up to 3 pounds of grain without any negative consequences. If more grain is fed, additional degradable protein will be necessary to reduce the negative effects of the grain on forage digestion. Use of fiber-based alternative feeds such as wheat middlings, soybean hulls, corn gluten feed, and distillers grains will allow producers to supplement energy and protein to the cows diet without sacrificing forage digestion. Each of these feeds can be easily fed at up to 15 pounds per cow per day. The high fat content of distillers grains limits their inclusion to 10 pounds of dry distillers grains, 17 pounds of modified distillers grains, or 25 pounds of wet distillers grains per cow per day.

Remember that cows will handle one or two days of very cold weather fairly well -- but sustained periods of three to five days or more are harder on the animals.

Keep in mind that cows' nutrition demands are greatest in the late stages of gestation, when most fetal growth and development takes place. Providing proper nutrition during this time can have a dramatic impact on the health and vigor of the calf as well as the cow's rebreeding.

"When Mother Nature unleashes a cold snap or a blizzard, providing those nutrients can be challenging," Wright said. "In the short term, nutrient deficiencies are not likely to cause problems. However, once the weather breaks, care should be taken to provide the necessary nutrients to get the cows back in shape."