High temperatures raise the concern of heat stress on cattle. Heat stress is hard on livestock, especially in combination with high humidity. Hot weather and high humidity can reduce breeding efficiency, milk production, feed intake, weight gains, and sometimes cause death. Livestock should be observed frequently and producers should take precautions when hot and humid weather is forecast. Work cattle early in the morning to decrease the risk of heat stress. A danger sign in cattle is panting. The panting mechanism in cattle does not appear to work as well as the one dogs' have.
Major management options are providing shade, improved ventilation and a sufficient quantity of water. Shade for livestock can be provided by trees, buildings or sunshades. The temperature can be further reduced by spraying cool water across the roofs of buildings where animals are housed. Ventilation can be provided for air movement by fans and windows. Sunshades should be high enough to allow air movement
Providing an adequate source of cool, clean drinking water is essential to help keep animal's internal body temperature within normal limits. It is thought that water temperature affects rumen temperature and thus blood temperature which affects brain centers that control feed consumption. Above-ground water lines should be provided shade by having taller grass cover them. Run lines in fields that are not be currently grazed to water troughs that are in fields being grazed. The manager should at least check the water temperature in the water trough. Temperature increases from 70oF to 95oF can increase total water requirements by about 2.5 times.
Producers using management intensive grazing might consider several options. One option is to rotate through fields at a more rapid rate. Taller grass tends to be a cooler surface to maintain cattle on than pastures with shorter grass stands. Another option is rotate cattle in the evening rather than the morning. The assumption is that the grass will be consumed in the evening and hopefully the "heat of fermentation" or digestion is mostly dissipated by mid-morning, thereby reducing the heat load produced by the animal. Another possible option is to graze paddocks that allow access to barns (shade) or trees during the heat of the day. This will reduce equal distribution of manure throughout the paddock but might be a suitable compromise during excessively hot weather.
A similar recommendation of feeding feedlot cattle in the evening rather than the morning may apply. Conversely, cattle may eat more during the night than during the day in hot weather. Cattle that look hot in the morning will not eat much that day. Any shift in feeding feedlot cattle needs to be done gradually. Keep in mind that concrete is hotter than dirt so you may need to check cattle more frequently that are predominantly on concrete than on dirt. However this situation is less of concern in Ohio where most feedlot cattle have access to some shade.