Be on the lookout for heat stress in herds, flocks

Livestock, poultry producers should be prepared with a heat stress management plan

As warmer weather approaches in the Northern Hemisphere, livestock and poultry producers need to be on the lookout for heat stress in their animals and find ways to combat it.

Heat stress results from the combination of elevated air temperature and humidity, which compromises an animal’s ability to dissipate body heat.

Heat stress can result in reduced feed intake and weight gain, poor breeding efficiency, lower milk production, increased disease susceptibility, and death in severe cases.

Heat stress affects the health and performance of high-producing livestock; for example, heat stress costs the U.S. dairy industry more than $800 million a year. Heat stress can have a major impact on sow performance and longevity and sows may feel heat stress at temperatures higher than 70F. Broilers reduce their feed intake under heat stress because digestion and metabolism of feed increases the internally produced heat.

Signs of heat stress in animals include:

• Bunching in the shade
• Salivating excessively
• Foaming around the mouth
• Panting
• Trembling or lack of coordination

Plan to combat heat stress

Livestock and poultry producers should have a plan in place to combat heat stress well before the temperatures start to rise. Some tips to help animals cope include:

• Provide shady areas so animals can get out of direct sunlight.
• Provide fans or allow for adequate air movement to improve ventilation.
• Always provide cool, clean drinking water.
• Use sprinklers to wet the animals, as well as the ground where animals lay to cool the area.
• In ruminants, move feeding time to late afternoon or evening to allow rumen fermentation, which creates heat, to take place during cooler temperatures.

There are specific practices that can help pigs cope with heat stress:

• Promote consistent feed consumption.
• Feed sows according to stage.
• Increase feeding frequency.
• Provide calories through fat vs. fiber.
• Evaluate trace mineral levels.
• Provide access to quality water.
• Keep feed fresh.

Additionally, use these practices in poultry production:

• Increase nutrient density
• Reduce excess protein
• Reduce fiber concentration
• Increase use of fat calories
• Utilize feed additives
• Feed pelleted diets

Benefits of live yeast in dairy cows, pigs

Live yeast has also been shown to benefit dairy cows and pigs suffering from heat stress. Ruminant-specific live yeast optimizes rumen pH and enhances feed efficiency thanks to better fiber utilization. A trial conducted under severe heat stress conditions indicated that live yeast fed to dairy cows improved feed efficiency by up to 7 percent. The same trial also indicated a positive effect on rumen pH, resulting in lower acidosis risk: 45 percent of cows had a pH lower than 5.8 percent in the control group.

In sows, probiotic yeast had a positive effect on growth performance under thermo-neutral and heat stress ambient temperature. However, the live yeast supplementation had a greater impact under heat stress as it was able to compensate for the negative impact of heat on pig growth, through a positive effect on feeding behavior.