During summer times, cows could face heat stress. Here are some of the main symptoms:

1) Decreased dry matter intake

• Cows will dramatically decrease dry matter intake during heat stress in order to reduce heat production from digestion and metabolism of nutrients.

2) Low milk production

• Milk production will decrease during heat stress.

• When cows are facing temperature-humidity index or THI of 65 - 73, milk yield loss will average around 5 pounds per cow per day.

• If THI reaches these levels for 30 days, lost milk income from a 150 cow herd can add up as much as $3,375 per year.

3) Impaired reproduction

• Heat stress will affect reproductive performance of the 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 order to prevent high economic losses during summer, there are a few steps that can be taken.

• Shade cuts solar heat gain for cows on pasture.

• Have shade for cows in barns as well.

• Make sure the barn ventilation is good as it will help cool the cows.

• Tunnel ventilation brings air in at one end and exhausts it out the other. Size fans and inlets correctly and make sure the fans are well maintained and inlets are open.

• Mixing fans can help to cool the cows by blowing air past the cows.

• Have high pressure misters to cool the air by creating a fine mist or small droplets. Droplets need to evaporate before they hit the stalls or bedding.

• Evaporative pads cool and humidify the inlet air in low-profile cross ventilation barns.

• The pads need to be uniformly moist for the best effect.

• Ensure there are fresh and clean water available to the cows at all times.