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WC DAIRY NEWS  CHRISTMAS 2024 27
Heat stress? On your farm? Yes. Yes.
Victoria Asselstine, Ph.D.
Ruminant Technical Service Consultant, Jefo Nutrition Inc.
Sarah Dean, M.Sc.
Ruminant Technical Specialist, Jefo Nutrition Inc.
Reflecting on last summer, can you
estimate your stress level? The beginning
of the warmer months usually comes with
a lot of questions, and stress... “Will my
cows tolerate the heat? Will their milk
production drop, how long will it take to
come back up? Will their reproduction
be impacted?” Are you always trying to
put in place ideas to help them deal with
heat stress better? Now that this specific
stressor is over, winter is the perfect time
to make some necessary and important
barn improvements to ensure that your
whole herd is setup for a productive
summer, with heat stress being less of a
stressor for you and your cows.
You can only improve what you measure.
The first step to understand what kind of
heat stress your cows might be enduring
is to monitor your barn and gather data.
Then, you can focus on ventilation, shade
and cooling to help your herd deal with
the specific conditions they are facing
in your barn.
Monitoring your Barn
Monitoring the temperature in your barn
is important to truly understand the
potential heat stress your cows are facing;
you may feel fine, but your cows might not.
There are ‘smart’ temperature sensors,
which can monitor barn temperature and
humidity levels, that alert you when your
cows are at risk of suffering from heat
stress, especially useful when you might
not be suspecting it. Cows begin to be
negatively affected by heat stress at only
24°C and 20% relative humidity. It is also
important to manage your barn’s stocking
density to reduce its added impact on
heat stress during the summer.
Ventilation strategies and
effective cooling
Implementing proper ventilation, shade,
and cooling systems (such as sprinklers),
can effectively reduce heat stress in your
herd. Consider the following preventative
measures to further minimize heat stress:
•  Ensure curtains open and close
efficiently
•  Vents are clean and providing maximal
airflow
•  Fans evenly dispersed throughout the
barn to create a consistent breeze
across the entire barn
•  Reflective roofing material to reduce
heat absorption into the barn
•  Overhangs, awnings, and shade curtains
can reduce direct sunlight into the barn
•  Sprinkler systems above feed bunks;
ensure water droplets are small, larger
droplets will leave cows wet without
effective cooling, potentially worsening
heat stress.
Important during the summer
months and for the future of
your herd
Not only is heat stress a concern for current
milk production, it’s also very important to
consider the effect on future performance
of your herd. Heat stress during the dry
period can lead to decreased performance
in the subsequent lactation (up to 4 kg/
day) due to compromised mammary
gland development. Heat stress during
pregnancy will also negatively impact the
calf’s future performance (studies have
shown decreased pregnancy rates and
reduced milk yield by 5kg).
Regardless of whether you have systems
in place, need to make improvements or
enhancements are not feasible at this
time, make sure your systems are clean,
and well-maintained for optimal efficiency
for your whole herd!
Nutrition: Another valuable
solution
During heat stress, your cows are wasting
energy trying to cool their bodies, however
we want your cows to use their energy
efficiently. B vitamins are co-factors that
speed up their metabolism, ensuring
maximum production of fats, proteins
and glucose from their ration. A solution
to ensuring cows have the nutrients and
vitamins they need to combat heat stress
and the negative effects of it, is to supply a
Protected Blend of B Vitamins. B vitamins
can minimize oxidative stress and improve
liver function, which is of critical importance
for heat stressed cows.
Want more information
on othe r ways to
help your herd deal
with heat stress?
Scan the QR code.References available upon request.