Former Extension Educator, Local Food Systems and Small Farms
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Tuesday, August 2, 2016
While we may be getting a slight break in the heat, heat stress could still be a real problem for livestock, we could be seeing summer's hottest temps yet to come.The greatest impacts of heat stress come when cattle are exposed to a combination of elevated temperature and humidity over a period of time. Hot and humid conditions during the day can stress cattle, but cooler temperatures at night serve as a relief from the heat of the day.
Cattle utilize involuntary regulations methods to maintain a normal body temperature, such as shivering and sweating. When an animal is unable to dissipate heat, heat stress occurs. signs that cattle are trying to maintain body temperature are an increase in respiration rate, increased heart rate and increased panting. Cattle may also decrease feed intake or go off feed entirely.
Producers can take the following steps to help protect cattle from heat stress:
- For pasture cattle, evaluate the condition of water supplies and ensure plenty of high-quality drinking water is available.
- Identify animals that are most susceptible to heat stress. They include feedlot animals closest to the market endpoint, very young and very old animals, and those with dark hides.
- Know when to intervene. A combination of factors, including temperature and humidity, drives heat stress.
Producers should also have an action plan to deal with heat stress. Some things to consider:
- Give each animal access to at least 2 inches of linear water trough space in a pen. This means that in a pen with 200 animals, you need to have 400 inches of linear water space. If your cattle have access to only small water troughs, add temporary space for additional water access during the summer.
- Ensure you have sufficient water pressure and flow capacity to keep troughs full during times of peak water consumption.
- 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 the cattle's lung capacity during the hotter daytime temperatures.
- If feeding once daily, consider moving feed delivery to the afternoon. If feeding multiple times daily, consider feeding a small meal in the morning and a larger portion of the diet later in the afternoon. Decrease the amount of feed offerings during and for several days after heat stress.
- Provide adequate air movement. Remove unessential wind barriers (portable wind panels, equipment, weeds and other objects) to promote better air movement. Having mounds in pens gives cattle more elevation and possibly access to a area with more wind.
- Cool the ground and the cattle gradually. Sprinklers cool the ground cattle are lying on as much as they cool the cattle. Set up sprinklers well in advance of anticipated heat stress because cattle take time to adapt to changes. Use the sprinklers during mildly hot days so cattle become accustomed to the sights, sounds and the cooling effects of the sprinklers. An alternative to sprinklers is running a hose into pens to wet the ground where cattle will be lying. Run the sprinklers or wet the ground before the day's peak temperatures.
- Be aware of the droplet size of water coming from the sprinklers. The goal is to have large droplets of water. A fine mist likely will make the pens even more humid and contribute to greater heat stress.
- Provide shade if possible.
- Add light-colored bedding (straw or corn stalks) to reduce the temperature of the ground on which cattle are lying. Apply bedding to the tops of mounds and other areas likely to have wind. Also, wet the bedding before or shortly after putting it out.
- Control flies as much as possible because hot cattle tend to bunch together, and flies will add to the stress of hot days.
- 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; postpone or cancel some working events.