LINCOLN, Neb. — A mild, rainy spring has yielded to heat, humidity and lack of moisture, and the state's livestock have begun to suffer the consequences.
Heat stress is hard on cattle and other livestock, especially when combined with high humidity and low wind speeds; those are precisely the conditions occurring in many areas now. Heat stress can reduce feed intake, weight gain, reproductive efficiency and milk production, while increasing susceptibility to diseases.
Signs of heat stress can include animals bunching, seeking shade, and panting, slobbering or excessive salivation, foaming around the mouth, open mouth breathing, lack of coordination and trembling, said Lindsay Chichester of University of Nebraska-Lincoln Extension.
If such symptoms are observed, handlers should assume the animal is suffering from too much heat and immediately try to minimize the stress to the animal, especially by reducing handling or movement of the animal. Previous health of individual animals is an important risk factor, as animals with past health problems will be more affected by heat stress than animals with no prior health problems. These animals will generally be the first to exhibit signs of heat stress and be the most severely affected.
As county fair season gets under way, Chichester said, there are several things people showing animals should keep in mind, beginning with the heat index commonly reported by media outlets.
If the heat index is above 100 degrees, animals can tolerate it if shade is available and/or wind speed is at least 10 miles per hour, so show animals should be provided shade and/or moving air via fans.
If the index gets above 110 degrees, animals will stressed regardless of wind speed. Show animals should be in the shade with fans, especially market ready animals, and have plenty of access to water. If a heat index above 110 is predicted, livestock shows should be completed by noon. In addition, livestock that need to be moved or transported should be out of the facilities by early morning but certainly by noon, if possible.
If the heat index is above 115 degrees, avoid moving or handling market ready animals. Livestock show rings should be shaded with fans and misters; the show staff should consider postponing the show due to excessive heat.
If the heat index is above 120 degrees, no activity should occur for animals or humans.
During the heat of summer, livestock management musts include providing: shade, ventilation and air flow, clean and cool water, wetting, cool water drench and sprinklers or hoses. Shade can be provided by trees, buildings or other sunshades. In addition, the temperature can be lowered by spraying cool water on the roof and walls of buildings where the animals are being housed. Improved ventilation can be provided by fans or opening windows on a breezy day. Sunshades should be high enough off the ground (10 feet or more) to allow for adequate air movement.
Chichester stressed that if one is wetting cattle, the droplet size should be large enough to wet the skin, not just the air. "A small droplet size will usually just wet the hair creating more humidity for the animal, thus not helping at all."
During times of heat stress, animals should not be subjected to too much activity, including movement or transportation.
More information is available at http://beef.unl.edu