Shade material evaluation based on physiological response of cattle

Authors: Eigenberg, Roger; Brown-Brandl, Tami

Submitted to: ASABE Annual International Meeting
Publication Type: Proceedings
Publication Acceptance Date: 8/5/2011
Publication Date: 8/7/2011
Citation: Eigenberg, R.A., Brown Brandl, T.M. 2011. Shade material evaluation based on physiological response of cattle. In: Proceeding for the American Society of Agricultural and Biological Engineers (ASABE) Annual International Meeting, August 7-10, 2011, Louisville, Kentucky. Paper No. 1111184.

Interpretive Summary: Weather events can affect cattle in open feedlots with hot days and full sun being especially stressful. Shade has been used to reduce this stress but knowing what shade material to use can be a challenge. A study was conducted using feedlot cattle to investigate the effect of several different shade materials in comparison to no shade at all. Polyethylene shade cloths providing 100% shade and 60% shade were used in two of the comparisons. A third shade material that was evaluated was a plastic snow fence that provided about 30% shade. An earlier study had shown that respiration rate is a good indicator of the stress level of feedlot cattle. An automatic respiration rate recorder was used to collect respiration information on the cattle in this study. The information collected showed that all shade materials reduced cattle stress but the 60% shade cloth was the most effective with a fifteen-fold reduction in time spent in the emergency stress category. This work will help feedlot managers provide cost-effective methods of reducing feedlot stress.

Technical Abstract: Cattle produced in open feedlots are vulnerable to a variety of weather events; under certain conditions heat events can be especially detrimental. Shade structures are often considered as one method of reducing cattle stress. A variety of shading materials are available; selection of a suitable material is difficult without data that quantify effectiveness of the materials on stress reduction. A summer study was initiated using 32 heifers under shade structures in conjunction with meteorological measurements to estimate relative effectiveness of various shade materials. The 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 two of the comparisons and consisted of 100% and 60% effective shading; one of the structures was fitted with a poly snow fence instead of shade cloth. Additionally, a reference treatment with no-shade was included with one pen of heifers. Eight heifers were placed into each of the four treatment pens with average weights of 491 ±30.9 kg at the start and 520 ±35.0 kg at the end of the treatment period. Three heifers per treatment were equipped with automated respiration rate monitors. Each shade structure contained a solar radiation meter as well as a black globe thermometer under the shade material. Additionally, meteorological data were collected as a non-shaded treatment and included temperature, black globe temperature, humidity, wind speed, and solar radiation. The data analyzed in this study were collected from June 16th through August 18th, 2011. Preliminary analyses of the collected data focused on the effect of shade upon the heifer’s respiration rate. An associated heat stress index was used to determine the effectiveness of the shading options. 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.