“All warm-blooded animals must maintain their body temperatures within a relative narrow range or comfort zone. When air temperature falls below this range the animal must expend energy to keep warm. As winter approaches, many animals develop winter coats as insulation against the cold. In the case of beef cattle, a heavy winter coat will provide protection against temperatures as low as 18 degrees.
At temperatures below 18 degrees the animal is stressed and begins to require additional feed in order to maintain body temperature.
Exposure to Winter winds will increase the need for additional feed. If the temperature reaches zero degrees and wind speed is 25 mph, the windchill is 44 degrees below zero.
Under these extreme stress conditions, animals require significantly more feed, are less efficient at converting this feed into energy, and are more susceptible to latent diseases or other health problems. In contrast, when windbreaks are present, the reduced wind speed in the protected zone reduces the windchill temperature to 15 degrees below zero. While some danger remains for young or newborn animals, danger to mature animals is greatly reduced.
Kansas cattle producers indicate, that on average, calving success increases by 2 percent if cows are protected by a windbreak. Canadian researchers found that cattle on winter range, in unprotected sites, required a 50 percent increase in feed for normal activities. An additional 20 percent increase was necessary to overcome the direct effects of exposure to a combination of cold temperatures and wind. Wind protection reduced these needs by half.
Researchers at Purdue University found that energy requirements for cows in good condition increased13 percent for each 10 degree drop in windchill temperature below 30 degrees. A similar study in Iowa on calves and yearlings Indicated that requirements for feed were 7 percent greater for those in open lots than for similar animals with shelter. Studies in Montana indicated that during mild winters, beef cattle sheltered by windbreaks gained an average of 34 to 35 pounds more than cattle in an open feedlot. During severe winters, cattle in feedlots protected from the wind, maintained 10.6 more pounds than cattle in unprotected lots.”
Winter protection on the south and east sides of the windbreak system. In contrast, summer winds are generally southerly, and since wind speed reductions on the windward side of windbreaks (the side towards the wind) are limited, livestock benefit from the southerly winds. If a windbreak Is designed properly, it can protect livestock from cold winter winds and still allow summer winds to circulate in the feedlot or pasture area, reducing potential heat stress to the animals. In the North Central region where winter protection of livestock is most critical, northerly winds predominate during the winter and early spring. Locating windbreaks on the north and west sides of livestock operations provides winter protection on the south and east sides of the windbreak system. In contrast, summer winds are generally southerly, and since wind speed reductions on the windward side of windbreaks (the side towards the wind) are limited, livestock benefit from the southerly winds.
By locating feed bunks 75 to 125 feet south of the inside row of the windbreak you avoid both winter and summer problems.”
By Vernon Quam and LaDon Johnson. North Dakota State University. Bruce Wight, Soil Conservation Service, and James R. Brandle University of Nebraska