Here is a copy/paste of an article I found interesting with dealing with the effects of heat.
Shade aids in cattle growth, producer profit
Drovers news source | Wednesday, May 19, 2010
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Don't underestimate the value of shade for beef cattle in the fescue belt according to Eldon Cole, livestock specialist, University of Missouri Extension.
Management intensive grazing, where larger pastures are reduced in size for more efficient use of the forage, can leave some pastures without shade. Cole says research shows that shade for cattle is both helpful and profitable in southwest Missouri.
Two years of shade research was carried out at University of Missouri's Southwest Research Center in Mt. Vernon with impressive results favoring shade.
According to Cole, in 2000 a group of spring-calving cows were compared using portable manmade, metal roof shade (8 ft. x 12 ft.) or no shade. The trial was done on both endophyte infected and endophyte free fescue.
The greatest difference showed up on the infected fescue where the shaded cows outgained the others by .72 pound per day for 84 days. The calves nursing the shaded cows also made slightly better gains, 0.17 lb. per day, but that was not significant. The trial ran from July 3 to September 25 and the animals were all black.
The most dramatic finding of the shade study was the difference in pregnancy rates at the end of the summer. The overall pregnancy rate was 87.5 percent for the cows given shade while it was only 50 percent for cows with no shade.
"The difference was more pronounced when only the endophyte infected pastures were considered. The elevated body temperature is likely the culprit for the drop in percentage bred," said Cole.
The following year, the same trial was conducted at the Southwest Center using 550 pound steers. The shaded steers gained 0.2 pound more per day for 84 days than the unshaded ones. As with the cows, the difference increased up to 0.35 pound per day when the shade, no shade comparison was made on the "hot" fescue pasture.
University of Kentucky researchers have also compared manmade shade to no shade pastures on fescue and fescue-alfalfa mixed fields. Their data shows daily gain advantages for the shade cattle as follows: 1.25 lbs. for cows; 0.41 lb. for nursing calves and 0.89 lb. for steers.
Arkansas researchers used dry, Brangus-cross cows in a June 12 to August 14 trial on Bermudagrass pastures to compare no shade (daily gain 1.47 lbs.); artificial shade (1.81 lbs. ADG) and tree shade (2.34 lbs. ADG).
"Shade trees can present a problem since cattle traffic can kill them and the manure will not be distributed around the pasture. Trees may also present a lightning risk," said Cole.
The bottom line on the economics of shade will be a farm-to-farm situation according to Cole.
Here are several considerations to keep in mind: pastures that have fescue toxicosis problems will definitely benefit from shade; shade response will be greatest in mid-summer; and cattle breeds, colors and even individual genetic differences will give varying differences in response.
