Managing Heat Stress in Dairy Herds: The Role of Housing, Nutrition and Behaviour

Higher average temperatures and increased humidity during warmer months can increase cows’ susceptibility to heat stress, affecting health and welfare, fertility, and milk yields.

In this blog, we share key insights from Galebreaker’s recent webinar, where animal welfare specialist Chloe Rodriguez was joined by Marie Haskell – professor in animal welfare science at Scotland’s Rural College (SRUC), and Mark Scott – owner of Cowcentric Nutrition Consultancy, to discuss the role of housing, nutrition, and behaviour in managing heat stress.

Quick tips for managing heat stress

• Monitor temperature humidity index (THI) in sheds
• Monitor cow behaviours for signs of heat stress
• Optimise natural ventilation
• Achieve uniform lighting
• Consider adjustments to nutrition and feed frequency
• Ensure easy access to cool water

THI: “If you don’t measure it – you can’t manage it”

Marie Haskell recommends using THI as a metric for measuring the risk of heat stress. “THI is easy to use and not only considers the temperature in cattle sheds, but also humidity levels.”

Animal health and welfare specialist, Chloe Rodriguez explains why measuring THI is becoming more important. “The number of heat stress events are increasing, however as we don’t see consistently high temperatures over the summer, cows aren’t acclimatising.”

“That’s why it’s really important to measure THI levels to detect heat stress early and manage it proactively. If you don’t measure it – you can’t manage it.”

Galebreaker and Philbro Health’s online Temperature-Humidity Index (THI) tool, THI-Live, is available to monitor the risk of heat stress across the UK, and Galebreaker’s heat stress advisory service provides farmers with expert advice from its animal health and welfare team, a THI sensor, and monthly heat map reports throughout the summer.

Assess the risk of heat stress in your area on THI-Live here and find out more about Galebreaker’s advisory services.

Behavioural and physiological changes

At a THI level of 68, cows can start to demonstrate signs of heat stress, which can negatively impact milk yield, fertility and wellbeing:

• Reduced feed intake & eating food that does not produce heat
• Increased intake of water: up to 1.2kg more water for every degree of heat above the typical ambient temperature
• Panting (increased respiration rate): anything above 40-60 breaths per minute suggest the cow is stressed
• Sweating
• Lying down for shorter periods of time
• Grouping in cooler and darker areas of sheds

The role of nutrition in minimising heat stress

Mark Scott, owner of Cowcentric Nutrition Consultancy suggests three things to consider when looking at the role of nutrition against heat stress:

• When to feed your cows
• What to include in diets
• What to feed to mitigate the impact

Diet adjustments to minimise the risk

Mark recommends the following to reduce the risk of heat stress developing:

• High quality forage: the fermentation load needs minimising, and fibre quality needs increasing.

“Some farmers may consider reducing the forage-to-concentrate ratio, by replacing forage with moist feed, but it’s important to maintain fibre to reduce the risk of acidosis.”

• Calcium soaps: provide energy, without adding to the fermentation load in the rumen.

“The key is to feed and protect fat.”

• Bypass starch: cows will use glucose as an energy source, as it doesn’t create much heat in their body, so keeping starch intake at the right level is crucial. Bypassing starches reduces the pressure on the rumen, however, too much can create high gut fermentation.

Using nutrition to mitigate heat stress

When heat stress is already an issue, Mark suggests adjustments to the cows’ diet which can counter the effects:

Feed less:

• Forage – increase the energy density of the diet

Feed more:

• Metabolic protein
• Minerals and vitamins – help to compensate for those lost in sweating
• Ruminant buffers and yeast products – counter acidosis and risk of Lipopolysaccharides (LPS)
• Osmolytes – maintain cell hydration
• Additives – support evaporative losses from skin and reduce metabolic heat load

Practical feeding tips

Follow Mark’s useful tips for feeding to protect cows against heat stress:

• Feed at least twice a day
• Feed more at cooler times (overnight)
• Provide cool water – ideally at a temperature of 10°C in a shaded area, with 10cm water trough space per cow. Ensure there’s a good flow rate to for freshness and to prevent shortages.

Don’t forget your dry cows.

Cows suffering with heat stress in late pregnancy can produce up to 4.5 kilos less milk than cooled cows.

“This can have massive knock-on effects for calves born from heat stressed dams such as being born earlier, reduced absorption of antibodies from colostrum to protect against disease and a lower productive lifetime – so cooling dry cows is really important,” emphasises Mark.

Housed environments are increasingly important

As more cows in the UK are being housed indoors, so the need to adjust conditions in cattle sheds to protect against heat stress is becoming increasingly relevant.

The THI inside sheds will be two to six points more than that outside, so by monitoring THI, farmers can take a proactive approach towards optimising housing conditions against heat stress.

Cow shed design for better air flow

Galebreaker’s animal health and welfare specialist, Chloe Rodriguez shares her insight on improving building environments

“We want to get high air flow into buildings to achieve a cooling effect, but also to improve air quality, reduce moisture and reduce the heat produced by animals.

“Natural ventilation principles are often forgotten about, but fresh air is free – so maximise it!”

To optimise on natural ventilation, she recommends the following cattle shed features:

• An exhaust – ridges should remove hot, stale air while preventing precipitation entry
• Inlets – side curtain systems help to get as much fresh air in as possible
• Good building orientation and position – avoid adjoining buildings to help air flow throughout sheds (recommended 30 metres apart) and position so that prevailing wind passes perpendicular to ridge to accelerate exhaustion and maximise air flow

Mechanical ventilation methods such as Positive Pressure Tube Ventilation (PPTV) are also a good way of achieving a cooling effect.

Discover Galebreaker’s PPTV systems and Variable Ventilation Side Curtain Systems

The importance of lighting in cow sheds

As cows tend to bunch up in dark areas they perceive as cool, lighting plays a pivotal role in optimising shed space during warmer periods. Chloe recommends the use of light ridges to provide uniform lighting throughout the shed and avoid hot spots in cubicles.

Discover Galebreaker’s LightRidge solution for uniform lighting and improved natural ventilation.

Look – think – act against heat stress

Chloe suggests three key stages to protecting cows against heat stress:

• LOOK: monitor the cows – what is their behaviour telling you?
• THINK: identify the risk of heat stress
• ACT: monitor the risk, adjust and implement solutions.

For more details on how to manage and minimise the risk of heat stress, contact our expert team or watch the webinar in full on our YouTube channel.