Perhaps the easiest way to help to prevent heat stress or even to reduce heat stress in dairy cows is to find ways to keep the cows cool. The most practical ways to accomplish this goal are to group the cows in shade or to provide ventilation or a cooling system in their holding areas or in other areas where they generally spend a great deal of time, such as feeding areas.
Utilizing fans and sprinkler systems can be a highly effective way to keep your dairy cattle cool. Of course, this will require a significant financial investment while increasing your overall operating costs. As such, it may not be a very practical solution for your situation. A less expensive option – and still a very effective option – is to install a basic ventilation system. Side inlet ventilation and ridge outlet ventilation can go a long way toward increasing air flow and helping your dairy cows to stay cool.
If you are not sure about the quality of the airflow in your buildings, you can quickly and easily conduct a test with the help of a smoke cartridge. This will also help you to better determine what other physical improvements you can make to help increase the overall comfort of your dairy cows. You may be surprised to learn that research has found that an airflow of as low as 10 km per hour can reduce the respiration rates in heat stressed animals by as much as 50 percent. That makes it a change that is certainly worth making!
In addition to the many visible signs associated with heat stress in beef cattle, there are also several invisible signs and effects of heat stress. While they are not visible to the eye, wellness checks may show these signs through various forms of testing.
Some of the invisible signs of heat stress in beef cattle include:
- Indigestibility of feed
- Increased peripheral blood flow
- Increased respiratory infections
- Increased susceptibility to parasitic and non-parasitic diseases
- Loss of bicarbonates
- Loss of electrolytes
- Lower ruminal pH
- Reduced response to intercurrent diseases or pathogens
- Slowed gut and ruminal motility rates, resulting in slow passage of feed through the digestive tract
- Slowed recovery from environmental stresses
- Stress hormones in the blood
Heat stress can also affect the reproduction of beef cattle. Not only can it alter the production of the reproductive hormones that are essential for pregnancy, but it can also change the balance of developing follicles in the ovary. Embryonic development can also be affected while gene function is disturbed. Lower conception rates and lower fertility in bulls is also associated with heat stress, as are increased foetal and postnatal mortality rates.
By closely monitoring the health and the activity of your cattle, you can better ensure they are not suffering from heat stress and its negative – even possibly fatal – effects.
Different genotypes of beef cattle have different characteristics associated with their zone of comfort. Overall, Bos Indicus breeds and their crosses have a better heat regulatory capacity than Bos Taurus breeds. This is largely due to their differences in metabolic rate as well as differences in food and water consumption, their sweating rate and differences in coat characteristics and color.
Visible Signs of Heat Stress
A number of visible signs are associated with heat stress. These include:
- Decreased Activity
- Increased Drinking
- Increased Urination
- Open Mouth Breathing
- Reduced Eating
You may also notice your cattle bunching in any shaded area that is available or aligning themselves with the sun if there is no shade. Alternatively, your cattle may begin bunching around water troughs or they may refuse to lie down. On the other hand, they may become unresponsive or become agitated and restless. Slower growth rates may also occur and even death if the heat stress is allowed to continue.
If you see signs of heat stress in your cattle, it is important to take steps to help reduce the heat load so your cattle are not adversely affected. This may include providing additional shade or water or even using fans to help cool them down.
With cattle being unable to dissipate their heat load efficiently, heat stress is a serious concern for those who raise them. In this three-part series, we will explore heat stress in beef cattle further, including how to recognize it so you can give your cattle the care they need.
Since the sweating mechanism of cattle is poor, they are forced to rely on only respiration to cool themselves. To make things worse, the fermentation process within the rumen generates additional heat that cattle also need to disperse. Due to their inability to effectively get rid of heat, cattle tend to accumulate their heat load during the day and then dissipate the heat at night. Therefore, if the nights do not get sufficiently cool, cattle cannot effectively dissipate the heat at all.
In addition to the temperature, the Temperature Humidity Index also plays a role in how heated your cattle can become. The Temperature Humidity Index includes factors such as relative humidity, ambient temperature and evaporation rate. When humidity increases, the cattle’s ability to complete evapo-transpiration is reduced. This ultimately increases the core body temperature while also decreasing the animal’s feed intake.
In the next part of this three-part series, we will explore visible signs of heat stress in cattle.