Cattle producers should be aware that forecasted weather conditions could result in significant heat stress issues in cattle. The US Meat Animal Research Center predicts danger or emergency conditions through most of South Dakota beginning Saturday, July 16 and extending well into next week. In addition to afternoon temperatures forecast in the mid to upper 90s, recent moisture and humidity increases the risk of a more intense heat stress event according to Extension Beef Feedlot Specialist Ben Holland. Although some cloud cover and isolated thunderstorms are forecasted for Sunday, many areas will be hot and sunny most of the day and cattle could really start to suffer on Monday and Tuesday of next week.
Cattle in feedlots are generally the most impacted in high heat conditions, and steps should be taken to prevent heating of cattle and allow cattle to adequately dissipate heat. Providing shade can reduce the amount of heat accumulation in cattle, but it is important to remember that shade is more effective when adequate air movement through the shaded areas is possible. The same kind of shelter that helps keep animals warm in the winter can be a detriment for keeping them cool in the summer. During hot summer days, cattle accumulate internal heat, which must be released during the night time. When nighttime low temperatures are above 70 degrees Fahrenheit, especially for extended periods of time, heat removal is not very affective.
According to Holland, "The most important thing cattle feeders can do to help cattle cool off at night is by sprinkling mounds in dirt pens late in the evening or at night. This provides a cool place for cattle to lay down, allowing the heat to dissipate. Cattle can be sprayed directly during the day as well, but if cattle are sprayed, large water droplets should be used. Too fine a mist will only add humidity and make problems worse."
Producers should provide extra water such as supplemental tanks to pasture or feedlot animals. Animals will congregate by water sources when it is hot, so more adding more water sources can spread animals out and allow every animal a chance to drink. The ability of the water system to deliver volume must also be considered and monitored, and alternative water methods for water delivery should be considered.
Dr. Kelly Bruns, SDSU Professor of Animal Science said, "Cattlemen need to start preparing for the heat today by figuring out what auxillary water sources are available if cattle need extra water to drink and how is water going to be delivered to sprinkle pen mounds and cattle." He added, "whether you need to work with the local fire department or borrow a water truck to carry water, this needs to be figured out before Saturday evening when it is likely that cattle will start showing signs of stress in some areas."
Producers should also avoid moving, processing, hauling, or otherwise handling animals in hot weather. If these actions are unavoidable, they should be done in very early morning hours. Getting cattle used to being sprayed while it is still cooler can help prevent panic and stress when they are sprayed later.
Symptoms of heat stress in animals range from mild to severe as conditions worsen. Initially, animals will increase their respiratory rate in an attempt to cool themselves. Increased salivation and open-mouth breathing will commence, and in severe cases of heat stroke, animals will become uncoordinated, weak, and go down and not be able to rise. When these latter symptoms hit, recovery is unlikely.
Some animals will likely be more severely affected than others. Producers should pay close attention to dark-hided animals, fleshy animals, or animals with histories of respiratory disease.
Heat stress symptoms peak in the early evening hours after the animal's body attempts to regulate its temperature and fails. Holland recommends, "The most important thing is to be prepared to take steps to intervene before severe signs of heat stress manifest themselves."
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