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Cattle Shades

University of California and United States Department of Agriculture

Abstract

The investigations show conclusively that the principal function of shade is to reduce the heat intake of the animals incident to the absorption of radiant energy from the sun. Air temperatures were about the same for all types of shades that did not make use of evaporative coolers.

In the order of preference and well-being of the cattle, the shades can be ranked as follows: (1) desert or evaporative cooler (Shade No. 2); (2) wetted burlap or galvanized iron roofs (Shades No. 3 and 4); (3) double roofed shade without spray cooling (No. 4, 1949); (4) hay covered shades, 12 10, and 8 feet high (Shades No. 6, 8, and 5), the highest shade being the best; and (5) plain galvanized iron roof and louvered shades (Shades No. 1 and 7).

The evaporative cooler gave the animals some relief from high temperatures and reduced the radiation heat load considerably, but the cost of constructing the three side walls and installing the motor driven fan was high. Also, the humidity during part of the summer tended to reduce the effectiveness of this type of cooling system. Sub-roofs with water sprays reduced the heat load but produced a definite sanitation problem. The galvanized iron shade (No. 1) reached a higher temperature and re-radiated more heat to the animals beneath it than any other material tested. A layer of hay over galvanized iron reduced the amount of radiant heat considerably.

Because of their greater exposure to the cool sky animals under high shades (10 to 12 feet high) received less radiant heat than those under low shades (7 feet high). Shades higher than 12 feet have the disadvantage of a fast moving shadow, necessitating the movement of cattle to heated ground.

For practical use in areas of low rainfall, the cheaper hay covered shades are adequate. Some hay covered shades constructed in the Imperial Valley of California are still standing after four years, with no repairs. Since the hay becomes heavy when wet by rain, the framework must be of fairly sturdy construction. In areas with heavier rainfall, aluminum or galvanized iron shades over a layer of hay will provide cool shade in the summer and protection from rain in winter.

¹ The authors wish to express their appreciation to Professor H. R. Guilbert, Animal Husbandry Division, and T. E. Bond, U.S.D.A., for their help in the preparation of the paper and to Emmett Layton, Assistant Herdsman.