Overview
As mentioned in Part 1, “Heat Stress: The Impact on Workers,” 2011 has been one of the hottest years on record, in all corners of the country and especially throughout the Midwest. For those whose life’s work depends on animals, it’s important to identify the risks associated with rising temperatures and humidity levels.
Heat stress in animals occurs when a combination of health and environmental factors prevent the dissipation of heat from the body. It can have devastating effects on your livestock and business, including health issues, decreases in production and fertility, high mortality rates, and other costs.
According to a July 2011 ThisWeekinAg.com article, symptoms for cattle, pigs, and poultry can vary, but basic methods of prevention and treatment are similar. These include shade, cool air, water and monitoring.
Major Risks & Symptoms
It’s not just about high temperatures, as humidity levels play a major role in creating risky conditions. Moderate stress can occur in temperatures ranging from 80-90 degrees, with a 50-90 percent humidity level. Other environmental factors include available shade, wind speed, solar radiation, ground cover and nighttime temperatures.
Also, individual animals can pose different levels of risk, including age, color, breed, overall health and wellness, coat type and length, disposition and much more.
While the signs of heat stress will vary by animal, the following symptoms provide a general overview of what to watch for:
- Increased body temperature
- Lethargy, lack of movement, decreased activity and reduced grazing during normally active periods.
- Open-mouthed breathing or panting.
- Increased salivating or sweating.
- Rapid breathing.
- Irregular behaviors.
- Reduced feed intake.
- Reduced production, performance, weight gain or fertility.
- Restlessness and crowding under shaded, cooler areas, or at water tanks.
- Increased mortality.
Prevention and Treatment
There are several ways to mitigate the risks of these conditions for your livestock. It should be noted that early stages of symptoms are not always evident, which highlights the importance of prevention during high-risk times.
- Identify high-risk conditions and closely monitor animals.
- Provide proper shade, which should reflect heat and reduce exposures to rising temperatures and direct sunlight.
- Provide proper ventilation.
- Provide constant access to clean water, with adequate amounts made available at a rate of at least 25 percent body weight per day.
- Install sprinkler systems that produce large droplets, running from 2-3 minutes every 20-30 minutes, but avoid creating muddy environments that can reduce an animals ability to regulate body temperature.
- Provide proper nutrition for extreme heat conditions. One example given was providing low-fiber diets for cattle during these times because dense feed generates less internal heat during digestion.
- Acclimate animals to hot temperatures over three to four days so they can adjust their feed intake and metabolism.
- Avoid transportation and exercise during periods of extreme heat. If this must take place, complete between midnight and 8 a.m.
The Livestock Weather Hazard Guide provides guidelines that indicate the potential of heat stress at different temperatures and relative humidity. The National Weather Service (NWS) and USDA publish seven-day heat forecasts for regions throughout the country, based on four weather parameters: temperature, humidity, wind speed and cloud cover.
Treatment for heat stress will vary due to the type of animal and severity of illness, but should include measures to remove the animals from the source of the heat, cool down body temperatures, and provide hydration and nutrition.
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