In extreme cold, cows will improve their metabolic rate to create heat to keep body temperature. In California, they often have to deal with some extreme warm weather which can cause heat stress. They prefer a very stable body temperature. They try to increase feed intake in an effort to meet their energy requirements. If they are not fed additional feed or the quality does not allow them to eat enough to meet their additional energy requirements, body mass will be burned to produce metabolic heat. Cows in sunlight will absorb a significant little more heat than a cow in shade.
Since cattle rely on respiration for a process to handle heat respiratory function is vital. Heavy cattle can’t handle heat stress in comparison to lighter weight cattle. Cattle should not be worked during times of extreme heat and only early in morning when it is hot. Cattle that is not used to sprinklers will try to avoid the spray. These animals also will bunch when they are hot, and flies and other stressors will increase the problem.
All the above mentioned problems can be resolved by applying recombinectics and create a type of cow that can better sustain extreme heat.
Here an article describing it: https://apnews.com/f628e7c65c794995b19977b7c1cdc10c