The summer heat is upon us, and we all know we should be cooling our cows.
Heat stress costs our dairies in numerous ways: lower milk production, poor reproduction, decreased dry matter intakes, rumen acidosis, lameness and more. But with more financial burdens in the current dairy economy, most dairymen face the challenge of where they should spend their money.
A heat abatement audit may be able to identify inexpensive ways to cool your cows while you get through these tough times.
Holding pen
Your first priority should be the holding pen. Ideally, you would have one fan for every 10 cows in this space. Fans should turn on at 65ºF and run continuously. Ideally, you would also have sprinklers and soakers over the cows, cycling on for one to two minutes and turning off for five to six minutes. These soakers would automatically start at 65ºF to 68ºF, depending on your outside temperature.
If you have never used water in your holding pen and cannot afford to install a system this summer, do what you can to wet these cows.
Evaporative cooling, the thermodynamic process of spraying water on a cow’s back and having fans blow air across it to cool the cow, does not have to be expensive. For example, a small herd I worked with had fans but knew they needed to cool the cows better in the holding pen and couldn’t afford a fancy setup.
They started out with a garden hose, spraying the backs of the cows once the holding pen was full. They saw a positive reaction to this, so they then attached a garden sprinkler to a 4-by-4 post and ran it during milking hours. It only took a month of stable production to afford better soakers. Most of the time, if you can keep cows from dropping the normal 10 to 20 pounds per day in the summer, you can afford these cooling systems.
Water
Water is key to cooling cows. If you can place extra water tanks anywhere a cow has access, it will help with heat abatement. The best place to put extra water troughs is where cows can access water immediately after being milked. A cow will consume 10 percent of its daily water requirement immediately after milking. By placing tanks where cows won’t bunch up, the flow back to their pens will not be disturbed.
But if you wait and let cows get back to their pens, you will either have too many cows at the nearest water trough, or they will go eat and then rest. We need them to drink water to cool them. If cows have long walks from the parlor, place troughs along the walkways.
Within the pens, ideally there are enough troughs to equal 3 linear feet per 10 cows, or about 4 inches per cow. Cows need to consume water in order to produce milk. In fact, for every 10 pounds of milk produced, they need to consume an additional gallon of water.
If you can’t afford sprinklers in the barns, think about soaking the cows as they leave the parlor. This could be a sensor that only sprays when a cow walks under it or a sprinkler spraying all cows on their way back to their pens.
You allow the cows another opportunity for evaporative cooling, and this works even better if you have some fans set up after the cow is soaked. Cooling cows with water is better than with fans alone. Combining both fans and water is the very best and most efficient way to cool your cows.
Fans
A perfect heat abatement system includes sprinklers over the feedbunk along with fans. Position fans over each row of stalls, including the outside row in a six-row freestall barn. I like to see 10 stalls between each fan, not 10 stalls between each fan on alternating posts, meaning there are 20 stalls between each fan.
The importance of placement becomes apparent during your heat abatement audit. Stand in the first stall and feel the wind from the fan. It will probably be 8 to 10 mph. Then stand in the last stall before the next fan. You will be lucky to feel any wind flow. Now imagine you are lying in that stall and there are eight cows between you and that fan.
If fans are installed correctly and by a reputable company, the directional air flow will always blow in the direction of your summer prevailing winds. However, I am often surprised by the number of dairies I visit with fans blowing against the headwinds.
Of course this is an easy fix: Just turn your mounts around. Don’t make your fans work harder than they have to. Proper fan maintenance is key. Replace belts and clean blades before the heat arrives.
Are your fans running overnight through the summer? They should be. Watch your cows. If they are panting, that means they have already endured a prolonged heat buildup. In fact, the temperature overnight needs to drop below 68ºF for longer than six hours for the heat to be released back into the environment.
If not, it is now a part of the cow’s heat load for the next day. Running fans overnight will help circulate the cooler outside air.
Automation
When you are seeking more cost-effective ways to cool cows, automation probably does not come to mind, but it should. All fans and sprinklers should be on thermostats and timers. You shouldn’t have to rely on someone to turn them on, especially by their own internal thermostat. Whenever there is opportunity for human error, you will have heat-stressed cows.
Milking order
Something that doesn’t cost you anything is matching your group milking order to maximize heat abatement. Make an effort to avoid crowding cows into the holding pen during the hottest time of the day. Since you can’t avoid milking cows altogether during this time, try to avoid milking the most sensitive groups of cows.
I advise my herd managers to milk their fresh cows first thing in the morning, followed by their high groups/breeding groups. However, if those cows start getting milked at 6 a.m. and then again at 2 p.m., you are not doing them any favors. Take another look at your milking order and see if you can milk these cows during the cooler hours of the day.
Reproduction
We all know heat stress has a negative impact on reproduction, sometimes affecting a cow months after the heat subsides. A lot of herds use more timed-A.I. protocols during hot weather, as finding cows in natural heats can be difficult. We still need healthy, cycling cows for synchronization protocols to work, but we can also make sure we are maximizing reproduction utilizing such protocols.
Making sure the right cow is getting the right shot on the right day is the key to a successful synchronization protocol. It is also important to use an 18-gauge, 1.5-inch needle to ensure all of the hormone is injected into the cow.
Make sure you are using the best protocol available. Most prefer the 14/12 PreSynch/2PGF OvSynch56 or double OvSynch protocols. Cows really struggle through the summer, so let’s give them the best possible opportunity to become pregnant.
Dry cows
There has been a lot of research confirming heat stress contributes to shorter dry periods and lighter birthweights. Inversely, cows cooled during their dry periods gave more milk in their next lactation. Not all farms can house their dry cows and are forced to put them out on pasture.
But are we doing as much as we can for them? Is there not just adequate but actually good shade for these dry cows? Do they have access to plenty of clean, fresh water?
In summary, it is widely known we must cool cows during the summer heat. During these low milk prices, we need to achieve this as economically as possible. We can’t afford open cows and production loss. Ideally, we would start cooling cows around the country in May and June and try to contain as much milk loss as we can during July and August.
Working in Florida, my very best herds still dip a little in July and August, but they recover quickly when the heat backs off a bit. I urge you to step back a little and think of ways to obtain your goals in order to achieve our mutual goal: a productive, pregnant cow. 
PHOTO: Cows will consume 10 percent of their daily water requirement immediately after milking. Photo provided by Melanie Herman.
Melanie Herman is a reproductive specialist and lives in Florida.
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