The summer of 2011 was one of the most costly in history for feedlot managers in South Dakota as a combination of heat, calm winds and humidity caused approximately 1700 cattle deaths. In some cases, winter windbreaks that serve to diminish wind velocity and catch snow from November through March, did not allow sufficient air flow in times of extreme heat and humidity during the summer months resulting in these losses.
Cattle shades may mitigate heat stress for cattle in feedlots and provide economic benefits in terms of continued gains and improved efficiency versus lots with no solar protection. Indications are that about a 20 degree air temperature difference can be realized through the presence of a shade. However, research at the University of Nebraska indicates that cattle without access to summer shades do compensate when weather cools again, although death loss during conditions as last summer can be significant.
Shaded area recommendations per animal vary considerably depending on the source of information. One manufacturer of a movable shade in Nebraska suggested that 15 square feet per head was adequate while researchers at the University of Nebraska recommend 20-40 square feet per head, recognizing that there is little benefit to overcrowded conditions. Feedlots in Australia, where shade use is common, suggest even slightly more area for cattle is required on the upper end of the University of Nebraska range.
Several factors should be included in any checklist when considering construction of a shade:
Shades are typically constructed toward the center of a pen to allow cattle access to shade as the shaded area moves across the pen during the day.
Designs that include a north-south orientation consistently provide dryer pen surfaces as the shadow provided by the shade moves over a greater area.
Constructing shades over or near waters is not advised.
It is highly recommended that areas beneath shade structures be regularly cleaned of wet manure to limit odor and ammonia production and maintain a desirable lot surface.
- Increased shade height will allow for greater air movement and cleaning with equipment but is more costly as well. Fourteen foot heights typically allow for both.
Galvanized or aluminum materials have been utilized in the past as roof materials as has slats. However, light-colored fabric is becoming the material of choice recently. It is effective in providing desirable shaded areas and is particularly easier to handle if the roofs are removed or rolled up in the winter.
Consulting with a feedlot engineer is recommended for anyone considering the construction of feedlot shades. When constructed and used properly, they can mitigate the stresses caused by extreme heat and humidity.
Source: Jim Krantz