Plan for Cold Stress in Beef Cattle

1/4/2014 7:00 AM

The last time I wrote a column for Lancaster Farming, it was June and we were right at the beginning of the typical range of time for summer heat stress for beef cattle.

Now, we are basically at the beginning of the typical range for potential cold stress.

Factors in cold stress include temperature, wind, rain, snow, mud, feed quality, feed quantity, body condition and adaptation.

Cattle can be amazingly tolerant of cold conditions, but there are certain times when the manager needs to be thinking about what can be done to mitigate stressful cold conditions.

This requires some knowledge of the science involved and a certain amount of common sense and experience.

The research literature refers to the lower critical temperature when describing the ability of cattle to withstand cold conditions. The LCT is the temperature at which maintenance requirements increase to the point where animal performance is negatively affected.

Various sources put this temperature at 18-20 degrees F. However, a fact sheet from North Dakota State University says that after adaptation, mature beef cows in good body condition during the middle third of gestation may have an LCT as low as minus 6 F during dry, calm conditions.

When the animal has a lighter coat, the LCT goes up. If the cow has a summer coat or is wet, the LCT is around 60 F.

Of course, we wouldn’t normally expect a cow with a summer coat to be subjected to winter. However, one of the complicating factors in the early October blizzard in South Dakota was cattle whose coats were not at a winter level.

Cold rains can happen in the winter, and a winter coat is almost useless when wet. When the coat is wet it loses its insulation factor, which is essentially air trapped between hair fibers.

Most stockmen know that an animal is usually better off in snow rather than cold rain.

Several sources concur that for every degree below the LCT a cow’s energy intake increases by 1 percent. Basically, the animal needs more energy to maintain itself.

What can a cattle manager do to make sure that animals are not subjected to unnecessary cold stress?

Protection from the wind is obvious. Wind chill can worsen stress from a cold rain. A well-ventilated building, stack of big bales, woods, brush, fencerows and hollows are all potential windbreaks.

Reduce muddy conditions to every extent possible. This can be difficult, especially in March. Mud has pretty much the same effect as rain in reducing insulation from cattle’s hair.

Use bedding to help keep cattle clean and to provide insulation from mud or frozen ground.

Rotate hay feeding areas if possible. Bale grazing is becoming increasingly popular in the U.S. and Canada. It involves strategically placing bales into fields during the summer or fall for winter feeding.

During winter, bale feeding is managed with step-in posts and polywire. If managed properly, this type of system may help avoid problems with mud in feeding areas.

In many situations, mud can’t be fully avoided, but at least try to establish a dry area that can be bedded where cattle can lie down. If you need assistance with mitigating muddy, heavy-use areas, contact USDA-NRCS to discuss ideas on what can be done to improve your situation.

Feeding programs may need to be tweaked in prolonged cold conditions. Be prepared for cattle to eat more. Cows normally consuming 2.5 percent of their bodyweight in hay may increase to 3.5 percent.

Provide higher quality forage if available. Digestibility and energy levels in the forage are the key things to focus on. Higher energy forage will help the cattle deal with increased energy expenditure.

Supplementing cattle with grain or by-products is another strategy, especially if the only forage available is low quality. A few pounds of grain may be all it takes, but discuss this with a nutritionist to make sure you don’t overfeed or underfeed the supplement.

If you have a large enough herd and ample facilities, it could pay to sort cattle. First-calf heifers and older, thin cows could be grouped together and fed better quality forage in a low competition setting.

Cows in better body condition could be grouped together and fed lower quality forage.

If your cattle are not in a self-feeding situation, timing of feeding may help with cold stress management. Feeding late in the day will increase heat production at night via eating and rumination.

Finally, cattle need access to water at all times, even in winter. Cattle on low-quality forages and inadequate water can suffer impactions.

Dave Hartman, is a Penn State Extension animal science and agronomy educator based in Columbia County.

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