As any farmer, rancher or stockman knows, when temperatures rise in the summer months, so does the risk of a heat stressed herd.
Heat stress can be costly – it can cause a loss of money stemming from production decline, sick animals that need treated, and, in extreme cases, the death of an animal. If you are a producer with a herd of dairy cows heading into a long, hot summer, you will want to know what heat stress is, what the warning signs are, and how you can alleviate this problem on your farm.
What Is Heat Stress?
Heat stress, according to an article by the Better Health Channel, occurs when the body cannot cool itself enough to maintain a healthy temperature. This can lead to problems such as heat rash, heat cramps, dizziness or fainting, heat exhaustion or heat stroke. Overexposure to hot, humid conditions or being in cramped quarters on a hot day with poor ventilation can cause heat stress in dairy cattle.
Dairy cattle are not equipped with good biological heat reduction systems – with a reduced ability to sweat combined with the fermentation process of the rumen that produces heat, they retain a lot of warmth throughout the day. This inefficient dissipation of heat from the body makes heat stress a real concern for the dairy herdsman.
Heat stress leads to a decline in milk production, weight loss, and a weakened immune system – but one of the biggest impacts it can have on the herd and the bottom line is a loss of fertility.
“One of the largest costs of heat stress is reduced fertility,” said Reagan Bluel, University of Missouri-Extension Regional Dairy Specialist for Southwest Missouri. Fertility is primarily compromised through early embryonic loss, she continued, and can be a direct result of heat stress. Humidity is often as much to blame as sheer heat – understanding the Temperature Humidity Index (THI) can help you predict the potential of heat stress on your herd.
Signs of Heat Stress
Knowing the warning signs of heat stress in dairy cattle can help you treat problems in a timely fashion. Heat stressed animals will begin to produce less milk, so monitoring your production levels closely and keeping an eye out for a decline is helpful in detecting the first signs of heat stress.
A heat stressed dairy cow will eat less, drink more, pant, urinate more frequently than normal and/or become very lethargic. Cows suffering from heat stress, Bluel noted, “often will stand more, which could have long term effects on hoof health that you might not see until early fall.”
Treating Heat Stress
Prevention is always better than a cure – so consider taking steps to reduce the risk of heat stress in your herd before the weather gets hot.
“Making sure you have provided ample shade in a clean environment with plenty of fresh air and more than enough clean water can help,” said Dawnnell Holmes of Real Farm Foods in Norwood, Mo. “Dairy cows can more than double their water intake in hot weather,” she added.
Some studies suggest increasing the density of a dairy cow’s ration to help her avoid heat stress – easing back on the fiber while still providing a balanced diet can lower the amount of heat created by digestion.
Finally, Bluel suggests investing in heat abatement tools – fans and misters are well worth the money when you consider the high costs that are associated with a heat stressed herd.
