Keeping dry cows cool

With summer temperatures on the rise we need to make sure cows are staying cool

With summer temperatures on the rise we need to make sure cows are staying cool. Cows experience heat stress when the humidity index rises above 68 degrees F. Research has been done to show that a high producing cow making 120 pounds of milk a day can produce 6,000 BTU’s of heat per hour. Think of every cow in your barn like a small heater that is running continuously and never shuts off. Heat stress in dairy cows whether they are milking or dry can reduce feed intake, lower conception, increase health issues associated with lower immunity and lower production.

Heat abatement is important in dry cows as well as lactating cows because management practices in the dry period determine the success in the lactation period and the health, growth and future performance of her calf. Most farmers have heat abatement protocols in place for their milking herd, but not the dry cows.

Dry Cows on Pasture

* Shade- shade should be available and managed to ensure the underneath surfaces do not become muddy which can be a health risk. When using a shade structure, provide at least 65 square ft/cow and these structures should be between 12 and 16ft tall. If shade comes from trees, they should be rotated by fencing them off to prevent mud pits. Mud pits lead to increased numbers of environmental bacteria and can result in mastitis.

 

 

* Feedbunk- Feed should be shaded to prevent spoilage and maintain the nutritional value. Keeping feed cool can also maintain/ increase feed intake, which is important in dry cows close to calving. Sprinklers and fans should be above the feedbunk on the side where cows stand, if possible.

Dry Cows in Housing Facility

* Ventilation and fans- Fans should be placed above feedbunk and freestalls or bedded pack. Air velocity in any barn should be about 4-6 MPH. If freestalls are used there should be a 1:1 ratio of stall rows to row of fans. Fans should be angled at 15 to 20 degrees.

* Barn Orientation- Barns should be built east to west to prevent direct sunlight shining into the barn. In the summertime, minimizing sunlight entry into a barn can be critical to improve cow comfort, freshness of feed and decreasing temperature within the barn.

 

 

* Sprinklers and water- Clean fresh water should be available for the cows’ consumption. Location of water troughs should be within 50 ft of resting area and should be in the shade. There should be 3 inches/ cow of trough space in the pen. Sprinklers should be placed along the feed bunk and soak the cow’s skin and are more effective when paired with fans. The ratio of on to off time is 2 min on for every 10-12 minutes off. Fans should run continuously once the temperature reaches 65 degrees F.

* Nutrition- Consult with your nutritionist to see if DCAD balancing your ration will work on your farm.

Why does this all matter?

* Cows calve 2- 8 days early when heat stressed. Research shows calves were 13 lbs. lighter and continued to have lower body weight and height through 12 months of age.

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Heifers born to heat stressed dames give less milk. Milk production can be up to 11 lbs. less than heifers born to dams that were not heat stressed.

* Lowers milk production in next lactation.

* Decreases conception rate.

* Lowers immune system. Fresh cows already have a compromised immune system, but those cows under heat stress have a greater risk of infection since immunity is even more compromised.

Heat abatement for dry cows is important and must be properly managed. Milk production, fertility and feed intake can be improved with adequate heat abatement.

Please contact Stacey Caughey, Interim Extension Educator for Stearns, Benton and Morrison counties with any questions at 218-330-5737 or butle269@umn.edu