Provided by the UT Extension Office
Article source: North Dakota State University Ext.
Being proactive is the best approach for dealing with heat stress in cattle. Once cattle are in a severe state of heat stress, you may be too late to help them. Having a solid management plan in place to address heat stress could pay big dividends in the form of maintained animal performance during periods of heat and in avoiding death losses in severe cases. Dr. C.R. Dahlen and Dr. C.L. Stoltenow with North Dakota State University Extension have developed a 3 step plan to help manage heat stress in beef cattle.
Step one: Identify animals that are most susceptible to heat stress. Animals that are overweight, very young and very old also are the most at risk. Animals with dark hides are at a higher risk of suffering heat stress and dying. Deaths of black-hided cattle on pasture without shade and limited supplies of water have been recorded. Know where the animals most susceptible to heat stress are before the danger of heat stress is present. Be prepared to have these animals as a priority in your prevention/intervention plan.
Step two: Develop an action plan for heat stress. The action plan is the essential actions you will take to protect the animals most susceptible to heat stress. The action plan should include the following:
• Animals in heat stress need to drink water. Make sure they have a plentiful supply of clean drinking water.
• Move the animals’ feeding time to late afternoon or evening. This will allow rumen fermentation to take place during the cooler night temperatures, and it will increase lung capacity for the cattle during the hotter daytime temperatures. Normal digestive processes create heat in cattle.
• Air movement is an additional factor that promotes animal cooling. A breeze or wind moving over the hide of cattle promotes evaporative cooling. Blocking or hampering the movement of air impedes evaporative cooling.• Provide shade. Solar radiation from sunny, clear skies contributes to body temperature in cattle. Providing shade stops solar radiation from increasing body temperature.
• Control flies as much as possible because hot cattle tend to bunch together and flies only will add to the stress of hot days.
• Maybe the most important, do not work cattle during temperature extremes. If working cattle is absolutely necessary, keep working time as short as possible, use calm animal-handling techniques to minimize stress related to handling, and consider running smaller groups through the facility or into holding pens. Provide sufficient water in holding pens. Get started as early in the morning as daylight will allow. Do not work in the evening after a heat-stress day; cattle need this time to recover. Reconsider the necessity of working cattle during these periods; some working events need to be postponed or canceled.
• Pay attention to long- and short-term weather forecasts and have a copy of the temperature humidity index chart readily available. Livestock weather index charts with temperature and humidity ranges can be found on the internet. Determine the potential risk threshold and be prepared, even if the risk is several index units away.
Step three: Know when to intervene. Heat stress is driven by a combination of factors. Temperature and humidity are two of the most frequently cited issues. Understanding that heat stress in cattle is cumulative is important. If the evening temperatures do not cool low enough, cattle cannot fully recover physiologically before the next onset of heat. Heat in summertime is not avoidable. However, you can take preventive measures when designing facilities and before temperatures reach dangerous levels to minimize impacts of heat stress on cattle.