By Randy Williams
Intense summer heat (much like what we experienced in July) make horses, cattle, sheep, swine, and goats especially susceptible to heat stress.
An animal’s body heat is maintained in various ways such as conduction, convection and radiation. Conduction is the transfer of heat through physical contact (laying on a cool floor for
instance). Convection is the movement of heat from the animal’s body to the air (helped by using a fan} while radiation is the emission of heat to and from the animal’s surroundings (intense heat radiating from a barn wall), directly from the sun. Evaporation is the transfer of heat through the conversion of liquids to a gas. This is often considered the most efficient heat transfer (horses and Brahman cattle’s ability to sweat); however, considering many livestock do not sweat, it may not be the most effective.
By knowing the different ways in which heat either escapes or enters the animal’s body we can begin addressing ways to manage these conditions in our livestock. Remember, when we ignore heat stress we take a risk. An over-heated animal is not maximizing its metabolism and thus poorly converting food to energy. This has an impact on weight gain, performance, egg production in poultry – you name it and I can pretty much assure you that high heat conditions will affect your animal projects.
So, what are we looking for in Heat stressed animals? Well, that varies depending on what kind of animal we are observing. Panting, or increased respiratory rate, are typical signs to look for. When an animal is overheated they “pant” to expel heat through evaporation. In their publication Livestock Heat Stress: Recognition, Response and Prevention (Kerr, 2015), Washington State University Extension mentions these other signs of heat stress to look for:
• Crowding around water tanks or shade
• Lethargy – “slow and lazy”
• Poor appetite
• Drooling or slobbering
• Staggering
• Non-responsiveness
• Elevated heat rate
• Collapse
It’s also important to note that various animals become susceptible to stress at various temperatures with cattle being the most sensitive – partially due to their large size. That said, according to an article in Livestock
Production Science “qualifying the severity of heat stress according to panting rate… appears to be the most accessible and easiest method for evaluating the conditions; all it requires is direct observations and a watch.” (Silanikove 2000).
Now that we know the signs of heat stress we can take precautionary measures to prevent it from occurring in the first place. Cattlenetwork.com gives some good advice in reminding us that the darker an animal’s coat the more susceptible they become to over-heating. Additional tips include:
• Keep water as cool as possible (locate in shade or erect a shade structure) and provide 1 gallon per 100/lbs body weight and double in extreme heat.
• Remember, when using a hose that is constantly full of water that the water WILL BE HOT when accessed. This is typically used to water swine with the addition of an access nipple. In this case, the
hose must be buried to prevent the sun from overheating the water…..EXTREMELY IMPORTANT TO
REMEMBER!
• Shear sheep in the Spring, allowing the wool to grow back slightly. This cushion around the animal actually shades the skin and reduces sunburn.
• Avoid working animals in the hottest part of the day.
• Invest in fans that are equipped with a water mist system.
• Provide as much shade as possible such as trees, or structures, but avoid putting cattle and other livestock in a barn as there is reduced airflow and intensified heat from congregating unless, of course, you are using fans or open windows or doorways.
• Provide mounds in pasture. Cattle will seek the top of mounds to be cooled by the air circulation.
• Time your feedings. Dr. Larry Hollis, professor and extension beef veterinarian at Kansas State
University’s Department of Animal Sciences and Industry remind us to also consider the metabolic heat load of livestock which peaks at around 4 hours in cattle. This means that if we feed them in the morning or mid-day they struggle with that heat load 4 hours later. Hollis recommends feeding a grain dominant diet in the evening or late afternoon as hay increases metabolic heat load (Hadachek, 2013).
• Get water on the animals. Use sprinklers in the field for cattle and mist units for pigs. A fine mist will often raise the humidity level and make conditions worse for cattle (again…use a fan with the mist). Larger droplet size allows water to reach the skin.
• Lastly, make fly control a priority! Flies cause livestock to bunch up and when doing so they cannot dissipate heat effectively.
I hope this information was useful! While it primarily addressed concerns with cattle, note that many of the above methods can be adapted to any livestock animal. Remember, that keeping your animals cool also applies to hauling them to and from the fairgrounds and at the fair. You will need to really “think” that one through and make a plan to prepare for the barns at the fairgrounds. Just use common sense. One more thing! Be careful when cooling off animals. Remember (especially swine) to avoid shock created from dramatic temperature changes. Cool animals slowly with water!
Be safe, stay cool, and “see you at the fair”!
Source: wsu.edu