Increasing Summer Gains of Livestock

Abstract

Methods of keeping livestock cool during the summer in the Imperial Valley of California were investigated in 1952 and 1953. The mean air temperature during the test periods was 91.8 degrees F. for the 1952 period, and 91.3 degrees F. for 1953. The temperature of the cool drinking water was 65±2 degrees F. for both years and the uncooled water averaged slightly over 89 degrees F. Work thus far shows that there are four ways of helping cattle keep cool and make faster gains during the summer. Shades made of an insulating material like hay, or a reflecting material like aluminum, are best for reducing the heat load on the animals. For best results shades should be 10 to 12 ft. above ground. Adequate shade for each animal is important, and at present it is felt that 60 square ft. of shade per animal is needed for cattle. Three years of experiments show that the steers that have access to cool drinking water will have a daily gain of from 0.26 to 0.44 lb. more than those on uncooled water. Three of the four tests completed were significant at the 1% level. A roughage-concentrate ration for cattle produces less increment of heat, and faster gains, than a roughage diet. Hereford steers on cold water and alfalfa hay gained 1.51 lb. per head per day, while those on cold water-hay plus grain made 2.01 lb. On warm water the hay group gained 1.18 lb. while the hay and grain lot gained 1.57 lb. These differences are statistically significant at the 1 percent level. Small heavy wooden corrals reflect and radiate enough heat to the steers to reduce their daily gains below those of animals in wire pens with some surrounding green vegetation. Measurements indicate an effective difference in environmental temperature equal to 5.5 to 6 degrees F. Work at this station has definitely shown that proper precautions will materially increase the daily gains of animals during the summer. This aid in some cases at first seems to be so insignificant as not to be worth the effort, but it does actually tip the animals heat balance toward the zone of thermal neutrality, as the daily gains show.