The summer heat is in full swing and here in Western Wisconsin all forms of life are looking for ways to cool themselves down.  We humans crank up the AC or buy an extra fan, dogs pant profusely and in the case of my hounds lie on their backs and play dead in front of the fan.  Backyard chickens run from shade to shade and cats often go unseen until the coolness of evening brings them back out into the open.  Excessive heat can be a burden to all of us but to a herd of cattle it can be destructive to both the animal and their owner’s pocket book.

Dairy Cattle during peak lactation utilize massive amounts of water and heat compounds this number.  Say a cow is producing 70lbs of milk a day.  Milk is around 87% water so in this instance the animal would be passing on nearly 61lbs (7.3 gallons) of water just in the production of milk.  This number does not count the water she needs to survive and function as a healthy animal.  The following chart is a guide line for water intakes during various temperatures and milk production:

Milk 45 Degrees Fahrenheit 85 Degrees Fahrenheit
Pounds/Day Gallons/Day Gallons/day
40 21 28
60 24 32
80 28 35
100 32 39
120 36 43

Keeping cows cool and drinking plenty of water is essential for maintaining animal health and production.  Animals stressed in any way will shy away from feed, but intakes drop off much more due to heat stress than other types of stress as more intake equals more digestion and digestion within a rumen produces lots and lots of heat, the last thing an already over heated cow wants.  When dry matter intakes (DMI) drop off, milk production follows very quickly.  On average one pound of DMI loss will result in 2lbs of milk production loss.  During times of extreme heat it is not uncommon for an animal to drop in milk production 25-50%; I do not know a dairy farmer today that can accept that big of a loss to their bottom line.

Aside from DMI and production losses how can you tell if your animals are experiencing heat stress??  One of the first signs is the herd’s behavioral changes such as lethargy, stubbornness to move, and crowding.  Later signs include heavy breathing and panting; if you witness these last signs the animal should be watched very closely and possibly looked at by a veterinarian.  Some herds will take extra steps once the heat begins to rise in efforts to track their herd’s heat stress level.  This can be done by selecting a group of 10 animals and testing their rectal temperatures every few days.  Temperatures will vary some but if a majority of the animal’s rectal temps are above 103 degrees Fahrenheit the cows are experiencing some heat stress.  Cows experiencing severe heat stress can show temperatures exceeding 104 degrees Fahrenheit.

Fortunately there are numerous ways that any dairy producer can help prevent and treat heat stress.  Prevention is always preferable and often cheaper than treatment and should be looked at first.  Methods will vary depending upon your particular housing but the basics stay the same.

Shade:  Cattle must have access to shade and should not be forced to travel long distances to get to it. Make sure that you’re feeding and water stations are near the shaded areas to minimize the time the cows will be exposed to the sun.

Water:  The most essential nutrient, resource, and element on the farm.  All animals should have easy access to clean water stations with ample space for multiple animals.  If you notice crowds forming around waterers you may want to consider adding more of them.  Cleanliness is also vital; if the water looks or smells bad to you; odds are your cattle feel the same.  Keep them clean and fresh and the herd will be more inclined to drink the amounts they need.

Ventilation:  Enclosed housing requires ample ventilation.  Fans should be used to keep a steady air flow moving through the barn; this will also help keep flies at bay!!

Electrolytes:  Electrolytes can be fed individually to cows that are showing severe signs of heat stress or added to the group’s water source at supplemental levels.  These products help the animals utilize fluids and replace key elements lost during dehydration such as sodium and potassium.

Probiotics:  Probiotics are recommended during all times of stress including heat stress.  Stress causes disturbances within the gut which can add to the animals already dwindling DMI.  Probiotics help keep the gut healthy and have shown positive effects on DMI.  Some bacteria strains have even shown to help reduce the animal’s core body temperature!!

One of the best things you can do is simply take extra time with your cattle and monitor them.  Go where they go; feed bunks, alley ways, holding pens, bedding areas.  If you are uncomfortable standing there you can bet your animals are as well.  Small changes can result in higher cow comfort which is never a bad thing for your animals or your wallet.