One-fourth of all of California's feed-lot cattle are in the Imperial Valley—a seemingly unfavorable environment for livestock production in the summer months. From June through September, daily temperatures average about 90° F., and frequently do not go below 80° F. Air temperatures above the animal's body temperatures may prevail for as long as eight or nine hours every day; and, because of the southern latitude and almost cloudless skies, the solar radiation is intense. But by good management practices involving corrals open to breezes, drinking water as cool as possible, proper rations, and well-designed shades, the Valley feeder has been able to obtain efficient gains.