Winter Cow Supplementation Options

By : Adele Harty, SDSU Extension Cow/Calf Field Specialist

Cold temperatures coupled with wind chill and precipitation make it challenging to meet a cow’s nutrient requirements during the winter months. February 2019 was an exceptionally cold month across the state, and it had a negative impact on cattle performance if supplemental energy was not provided at high enough levels to maintain body heat. The seasonal climate outlook released on January 16, 2020 indicates a slight chance of below normal temperatures and above normal precipitation for most of the state from February 2020 through April 2020. With this information, ranchers need to plan accordingly and be prepared to provide additional feed.

As the winter months progress, there are a few things to keep in mind and simple practices that will help ensure supplementation is done the most cost effective and efficient way possible. First and foremost, test winter forages to determine quality. The record precipitation from 2019 had an impact on forage quality and in some cases it was a negative impact. The forage analysis may cost $25, but it could save a lot of money in the long run. Use proper sampling procedures to ensure a representative sample. The results are only as good as the sample.

Next, monitor body condition score of the cowherd on a regular basis. For example, every 10 days or two weeks, after the cows are fed, drive back along the feed line and body condition score every 5th or 10th cow and average it. While keeping a running average, trends can be observed. Realize different cows will be scored each time, but the herd average will indicate the direction the herd is moving as a whole. If the average is 5.2, then 5.0 two weeks later and 4.7 two weeks after that, there is an energy deficiency that needs to be addressed immediately. This 0.5 BCS equates to approximately 50 pounds of weight loss in a month.

If significant body condition loss is observed, a supplementation strategy needs to be determined. In most cases, lost body condition is associated with an energy deficiency, but it could be associated with a protein deficiency that inhibits the rumen microbes from effectively utilizing the energy that is available. A forage analysis will help identify deficiencies so that an effective supplementation strategy can be developed. Refer to the article Clearing up Confusion on Protein and Energy Supplements to identify the appropriate supplement for the situation.

Now to account for the colder and wetter weather, the cow’s hair coat has to be considered as this will determine lower critical temperature. The table below shows the temperature at which cattle have to expend more energy in order to simply keep warm. This is adapted from D. R. Ames, Kansas State University.

Coat Description Lower Critical Temperature (LCT)
Summer Coat or wet 59 degrees F
Fall Coat 45 degrees F
Winter Coat 32 degrees F
Heavy Winter Coat 18 degrees F

Research indicates that for every degree below LCT, the cow’s energy (TDN) intake needs to increase by 1% to maintain herself. A wet hair coat can increase this energy requirement further. An example with recent temperatures at 5 degrees F, the cow’s energy intake would need to increase by 13% if she had a dry heavy winter coat. If additional energy is not provided to overcome this draw on the cow to maintain herself, she will start losing weight. If the cold lasts for an extended period of time, the weight loss could be significant and potentially affect health and reproduction in the future.

The take-home messages are to test feeds to determine nutrient content and adjust rations to meet the needs of the cows. If extreme cold or wet weather are in the forecast, be proactive in providing additional energy to assist those cattle so that they don’t lose significant weight during this time. Finally, feeding the cows supplemental energy will help ensure they will remain productive and healthy.

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