Shade material evaluation using a cattle response model and meteorological instrumentation |
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Authors: | Roger A Eigenberg Tami M Brown-Brandl John A Nienaber |
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Institution: | (1) US Meat Animal Research Center, USDA-ARS, PO Box 166, Clay Center, NE 68933, USA |
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Abstract: | Shade structures are often considered as one method of reducing stress in feedlot cattle. Selection of a suitable shade material
can be difficult without data that quantify material effectiveness for stress reduction. A summer study was conducted during
2007 using instrumented shade structures in conjunction with meteorological measurements to estimate relative effectiveness
of various shade materials. Shade structures were 3.6 m by 6.0 m by 3.0 m high at the peak and 2.0 m high at the sides. Polyethylene
shade cloth was used in three of the comparisons and consisted of effective coverings of 100%, 60% with a silver reflective
coating, and 60% black material with no reflective coating. Additionally, one of the structures was fitted with a poly snow
fence with an effective shade of about 30%. Each shade structure contained a solar radiation meter and a black globe thermometer
to measure radiant energy received under the shade material. Additionally, meteorological data were collected as a non-shaded
treatment and included temperature, humidity, wind speed, and solar radiation. Data analyses was conducted using a physiological
model based on temperature, humidity, solar radiation and wind speed; a second model using black globe temperatures, relative
humidity, and wind speed was used as well. Analyses of the data revealed that time spent in the highest stress category was
reduced by all shade materials. Moreover, significant differences (P < 0.05) existed between all shade materials (compared to no-shade) for hourly summaries during peak daylight hours and for
‘full sun’ days. |
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