The temperature humidity index is calculated to help producers know when to avoid putting cattle in situations of undue stress and danger. It is extremely helpful in making decisions as to when to work cattle, such as weaning fall-born calves. The weaning process can be stressful enough in pleasant weather; but when combined with a high temperature and high humidity index, it can be fatal.
If weaning calls for cattle to be gathered and put through a working chute for immunizations, implanting, dehorning, or other operations, then a few common sense rules should be followed.
1) During hot weather, cattle should be worked before 8:00 a.m., if possible. Certainly, all cattle working must be completed by about 10:00 a.m. While it may seem to make sense to work cattle after sundown, they may need at least six hours of night cooling before enough heat is dissipated to cool down from an extremely hot day.
2) Cattle that must be handled during hot weather should spend less than thirty minutes in the working facility. Drylot pens and corrals loaded with cattle will have very little if any air movement. Cattle will gain heat constantly while they are in these areas. Therefore, a time limit of one-half hour in the confined cattle working area should limit the heat gain and thus the heat stress.
3) Make every effort to see that cool, fresh, water is available to cattle in close confined areas for any length of time. During hot weather conditions cattle will drink more than 1 percent of their body weight per hour. Producers need to be certain that the water supply lines are capable of keeping up with demand, if working cattle during hot weather.
