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Controlling Heat Stress in Dairy Cattle

Posted on April 17, 2020
close-up photography of brown cattle during daytime

Dairy farmers in places such as the US and the Middle East have long had to deal with the effects of adverse temperatures on their cows. In the UK, however, our moderate climate has largely insulated us from these issues.

Now though, with global temperatures on the rise, UK dairy farmers are increasingly likely to face similar issues. Higher temperatures and altering weather patterns can have extremely adverse effects on cattle.

Heat Stress

Dairy cows have a set thermoneutral zone within which they will be the most comfortable and therefore the most productive. Fortunately, dairy cows have quite a wide comfort zone, ranging from -15⁰C (Lower Critical Temperature/LCT) to +25⁰C (Upper Critical Temperature/UCT).

Below the LCT, cows will increase their food intake, converting more food into heat, rather than into milk, decreasing yields.

These temperature fluctuations cause the cows to suffer from heat stress, negatively affecting their health and productivity.

Above the UCT, cows normally have two main methods for temperature control:

  1. Increase heat dispersion – this is achieved primarily through evaporation, an increase in subcutaneous blood flow, and drooling. These activities increase the maintenance needs of the animal by up to 20%. This means that milk production drops as more energy is redirected to thermal regulation.
  2. Limiting heat production – cows can also limit their heat production by reducing all movement and changing their feeding patterns. They will likely eat less, and be more selective about what they eat, consuming less roughage as this will cause the production of more heat in the digestion process.

Effects of Heat Stress

Universally, physical stress such as heat stress causes energy to be diverted to other needs. It will also lead to decreased fertility, including an increase in embryonic loss.

Unhelpfully, cows producing higher milk yields will also produce greater amounts of body heat.

Symptoms of Heat Stress

Those animals suffering from heat stress will exhibit a range of obvious symptoms. They will become lethargic and inactive.

They will also often stand with their heads bowed and pant in an attempt to increase evaporation. Perversely, cows suffering from heat stress will tend to gather together, worsening the effects.

Relative Humidity

Often overlooked in the measure of heat stress in dairy cattle is relative humidity (RH). Animals subject to high levels of RH are likely to exhibit symptoms of heat stress at a lower ambient temperature.

High levels of humidity will affect the cow’s ability to regulate its temperature, as activities such as panting, and evaporation become less effective.

RH is frequently above 80% in the summer in the UK and can regularly reach nearly 100% within poorly ventilated accommodation in the winter months.

Controlling Heat Stress

As temperatures rise, UK farmers must find a way to ensure their dairy cows do not become uncomfortable and therefore stressed.

This will decrease yields, lowering productivity and resulting in dramatically dipped welfare standards for the animals.

For those farmers who tackle the heat regularly, methods such as fans and water misting can lower body temperatures by as much as 1.7⁰C.

While methods such as these can prove effective to a point, the challenge for farmers comes in finding methods that deliver the necessary results, while avoiding incurring extra damage to the environment, as this would only serve to exacerbate the situation.

What can be done, is to establish temperature and humidity monitoring systems to ensure that when conditions do reach an uncomfortable level, action can be taken.

Whether this is through automated ventilation and misting systems connected to the sensors, or through an alert, bringing your attention to the issue so manual changes to the situation can be enacted.

At Omni Sensors and Transmitters, we stock and supply a wide variety of expert sensors and transmitters to suit a range of agricultural and industrial applications,

Contact us today to learn more about how you can fight heat stress in your dairy cattle, ensuring yields remain high.

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