With hot summer weather ahead, Robert Collier, Ph.D., reminds dairy producers of the importance of managing dairy cattle to minimize the negative impacts of heat stress that may inhibit immune function, impacting their health and productivity.
“Heat stress is a health and economic issue in every dairy-producing area of the world,” said Dr. Collier, professor at the University of Arizona Agricultural Research Center. “Production, reproduction and animal health are all impaired by hyperthermia. During heat stress, respiration rates and body temperature increase, while feed intake, milk yield and reproduction decrease.”
Speaking at a pre-conference symposium sponsored by Prince Agri Products, Inc., at the 25th Annual Florida Ruminant Nutrition Symposium in Gainesville, Dr. Collier said heat-stressed dairy cows may experience increased levels of the stress hormone, cortisol, which can weaken their natural immune system and make them more susceptible to disease and infection. “High somatic cell counts and a high incidence of clinical mastitis are associated with the hot summer months,” he said.
He noted that decreased milk production is linked in part with reduced feed intake, as well as metabolic changes, during extremely hot, humid weather. “In heat-stressed dairy animals, an increased metabolic rate causes a reduction in the metabolizable energy that is available for milk production,” he explained.
Dr. Collier also summarized results of a recent heat stress research project at the University of Arizona, which involved feeding an immune-boosting nutritional supplement to Holstein cows housed in controlled environments. Animals that received the nutritional specialty product, OmniGen-AF®, from Prince Agri Products had significantly greater dry matter intake, reduced respiration rates and lower rectal temperatures during heat stress, compared to control cows. They also had lower somatic cell counts after heat stress during the recovery period.
These data support the practice of OmniGen-AF supplementation as a critical component of modern dairy management to help maintain herd health; and that its everyday use may reinforce a dairy herd’s immune system so that unforeseen stress challenges will have a minimal impact on the cow’s susceptibility to disease.
In addition to supporting immune function, dairy experts recommend diet modifications for managing heat stress, such as adding supplemental sources of fat or utilizing lower-fiber feedstuffs to help reduce the heat of digestion. They also encourage producers to provide an adequate source of cool, fresh water, adequate shade, air movement and sprinklers, to promote cow comfort and help animals better tolerate a hot environment.