Tactics to keep dairy cows free from heat stress

Tactics to keep dairy cows free from heat stress

Jimmy Goldie, Chief Technical Officer at Carr’s Billington, advises on how to keep cows cool as a September heat wave looms and threatens herd health, fertility, and productivity.

August, despite its traditional warmth, has felt much more like autumn than summer this year.

But recent forecasts have indicated that sweltering heatwave conditions climaxing into the 30’s are to reach parts of the British Isles this September. And with heat stress impacting dairy cows from temperatures as low as 14°C when humidity levels are high, now is the #TIME2KEEPCOOL and ensure your cows have what they need to carry on milking.

How heat stress effects dairy cows

When the core body temperature of the dairy cow is raised above its normal range, the metabolic and immune system are compromised. The energy is prioritised away from normal function to means of keeping cool.

To make matters more extreme, the modern productive dairy cow is like an athlete and therefore tends to have a higher metabolic rate, and in turn, generates more heat.

Furthermore, cows are currently unacclimatised to higher temperature coupled with greater humidity levels, and so will suffer a greater shock when the heatwave comes.

When humidity levels are at 60%, performance is affected as follows:

at 14 degrees oestrus behaviour is affected
at 20 degrees conception is affected
At 22 degrees milk yield and quality is affected

Here’s what you can do now to avoid these signs and negative impacts in your dairy cows:

Focus on cow comfort

Whether your milking cows live in all year round or are out grazing, the key to managing heat stress is to provide them with the most comfortable surroundings possible. Here’s some quick fixes that you can implement straight away:

1. Provide access to shade in the way of trees, hedgerows, sheds and coverings.
2. Ensure adequate air flow by opening sheds up as far as possible.
3. Reduce stocking density and reduce group sizes in collecting yard.
4. Ensure water troughs are super clean and waterflow is optimised.
5. Hose cows down when they enter the collecting yard.
6. Feed in the late afternoon or early evening.

Longer term investments include installation of fans in buildings, installation of extra water troughs and other building adaptations such as removing roof ridges.

Prevent dehydration and stress damage

Heat stress increases the production of oxidants, causing oxidative stress and lipid peroxidation of cell membranes. This imposes a threat to the immune system and the reproductive function.

Equaliser® CoolCow is a unique blend of internal cooling elements, buffering agents, and alkalising ingredients designed to help prevent internal heat stress.

Maintain normal rumen function

When cows hit their upper thermal limit, saliva production is suppressed, causing sub-optimal rumen acid levels:
pH 6.2 to 7.0 – neutral to slightly acidic and ideal for all rumen microbes
pH < 6.2 – fibre-digesting bacteria begin to slow down
pH < 5.4 – fibre-digesting bacteria die out and lactic acid bacteria increase

Increasing the nutrient density of the diet to compensate for the lower dry matter intakes can compromise the rumen environment and function. TechTonic® is Carr’s Billington’s own rumen conditioner designed to help improve rumen pH, and in doing so, reducing the risk of sub-optimal rumen conditions and SARA.

Increase by-pass protein content

As rumen function is impaired, we advise increasing the by-pass protein content of the diet.

AminoMax-Pro is Carr’s Billington’s high DUP (Digestible Undegradable Protein) feed material, unique in the fact it is manufactured using natural ingredients rather than being formaldehyde treated. This patented process improves the DUP content of both soya and rape by heating them in the presence of sugar and steam. Sugars bind to the protein and block digestion in the rumen. Acid in the abomasum then releases the protein from the sugar allowing full digestion and absorption of essential amino acids.

Boost highly metabolizable energy

Certain foods will exacerbate the heat that’s produced from digestion, and others will have the opposite effect. High-fibre forages will require much more chewing and cudding to break down for digestion than low fibre supplements, generating greater heat per unit of energy.

Megalac is a protected fat supplement that is gentle on the rumen. It doesn’t ferment in the rumen, which means cattle get the benefits of an energy-dense feed without the associated heat production as with other nutrient sources.


By adding these ingredients to your ration or concentrate meal, you can help maintain production and fertility throughout periods of heat stress. Take advantage of our trusted advisors trained to help keep your cows cool and able to carry on.

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