Heat stress abatement on dairy farms is crucial in the summertime
Heat stress abatement on dairy farms is crucial in the summertime, and now is the time to think about it.
So what’s the big deal with heat stress? Well, it can have a huge economic impact. The three main heat stress symptoms driving economic loss are:
* Decreased dry matter intake. Dairy cattle will significantly decrease dry matter intake during heat stress in an attempt to reduce heat production from the digestion and metabolism of nutrients. It is important to develop a nutrient dense ration during periods of heat stress.
* Low milk production. Milk production can be significantly reduced during heat stress. When cows experience days where the temperature-humidity index, or THI, is between 65 and 73, milk yield loss averages 5 pounds per cow per day. According to this projection, during a summer in which the THI reaches these levels for 30 days, lost milk income from a 150-cow herd can add up to as much as $3375 per year, based on $15.00 per cwt.
* Impaired reproduction. Heat stress hinders reproductive performance of the dairy cow and consequential impacts can be seen for months following the exposure. Decreased fertility can lead to more days open and disrupt the cycle to which a cow enters and exits the milking herd. In addition, embryo loss is 3.7 times more likely in times of heat stress. A single cow’s pregnancy is worth an average of $450; however, this value can vary based on a cow’s age, future production potential and days-in-milk.
There a lot of facilities-related components that go into heat abatement. Think like an engineer to make sure you don’t miss anything. Here are some tips:
* Shade cuts solar heat gain for cows on pasture. Cows in barns have shade. Roof overhangs provide more shade near the barn sidewalls.
* Barn ventilation cools cows by providing air exchange between inside and outside. Ventilation can be by either natural or mechanical means. In hot weather, provide as much ventilation as you can.
* Mixing fans hung from rafters or trusses create air movement during hot weather to help cool cows by blowing air past the cows. Mixing fans do not provide air exchange between inside and outside but they supplement the cooling effect of ventilation.
* Low pressure sprinklers along feed bunks or in holding areas wet the cows’ backs to provide cooling. Wet the cows’ backs to the skin. Low pressure sprinkler systems must turn on and off. Cow heat evaporates the water and cools the cows when the sprinklers are off. Mixing fans enhance the effect. At 70°F sprinklers should be turned on at a cycle of 2 minutes every 15 minutes. As temperature increases, sprinklers need to cycle at shorter intervals.
* High pressure misters cool the air by creating a fine mist or small droplets. The droplets need to evaporate before they hit the stalls or bedding. Place misters near inlets. Misters are not as effective when ventilation blows the mist out of the barn before the air cools.
* Evaporative pads cool and humidify the inlet air in low-profile cross-ventilated barns. The pads need to be uniformly moist for best effect. Fresh water needs to be added, and check for mineral accumulation and algae growth.
As always, and especially in summer, cows need plenty of access to fresh water. There should be 1.2-3.6 linear inches of space per cow at a waterer. As temperatures increase, so does water consumption and crowding at waterers can occur. Ensure you have enough space at each waterer, as well as enough waterers. In freestall barns with 4 rows, waterers at every crossover are adequate. Understanding barn and pen design, as well as stocking rates will allow you to make the right decisions when it comes to waterers. Also, think about having a waterer just outside the parlor. Cows consume about 10% of their daily water after milking.
There are a lot of components to keeping cows cool and reducing economic impact in the summer. Prepare for the dog days of summer now by checking all fans, sprinklers, and waterers to make sure they are working properly.