Article by Melanie Herman, Premier Area Sales Manager and Reproductive Specialist in Florida (article originally featured in Progressive Dairy)
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 on where they should spend their money. The first thing you can do is perform a heat abatement audit on your farm. List the priorities and find an inexpensive way to cool your cows while you get through these tough times.
Holding Pen
Your first priority should be your holding pen. Here, cows are crowded together while waiting to get milked, sometimes for one to two hours. Ideally, you would have one fan for every 10 cows in this space. Fans should turn on at 65°F and run continuously. Ideally, you would also have sprinklers/soakers over the cows that would come on for one to two minutes and turn off for five to six minutes. These soakers would automatically start at 65°-68°F 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 in order to cool her- does not have to be expensive. I had a small herd once that 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 and would spray 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 4×4 post that they would run during milking hours. It only took a month of stable production to afford better soakers. Most of the time, if you can keep your cows from dropping the normal 10-20 lbs/day in the summer, you can afford these cooling systems. You just need to take it one step at a time to get there.
Water
Water is the most important 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 her daily water requirement immediately after milking. If you can place the 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, try and place troughs along the walkways. Within the pens, ideally you would have enough troughs to equal three linear feet per 10 cows, or 4” 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. Whether this is 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 she is water 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.
Cows will consume 10 percent of their daily water requirement immediately after milking.
Fans
A perfect heat abatement system includes sprinklers over the feed bunk 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 eight to ten mph. Then stand in the last stall before the next fan. You will be lucky to feel any wind flow. Now, imagine that 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 airflow will always blow in the direction of your summer prevailing winds. However, I am always surprised by the number of dairies that I visit whose fans are 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, clean the blades, etc. before the heat arrives.
Are your fans running overnight through the summer? They should be. Watch your cows. If they are panting, that means that they have already endured a prolonged heat buildup. In fact, the temperature overnight needs to drop below 68°F 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. Keeping fans on 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 herds 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 that heat stress has a negative impact on reproduction, sometimes affecting a cow months after the heat has subsided. 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 in order for synchronization protocols to work, but we can also make sure we are maximizing reproduction utilizing such protocols. Making sure that 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 11⁄2” needle to assure 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 that confirms that heat stress contributes to shorter dry periods and lighter birth weights. Inversely, cows that were 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 that 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 could 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 little. I work with my herds to make the best heat abatement plans that will work on their farms with their resources. 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.