10 tips to keep cows cool in the summer heat

Summertime is great for eating ice cream, but the heat and humidity can be dangerous for dairy cows, lowering milk production and threatening their health, said Dr. Meggan Hain, Staff Veterinarian at Penn Vet's Marshak Dairy at New Bolton Center.

Dr. Hain offers these 10 tips to help to beat the heat and to alleviate heat stress in dairy cattle:

1. Plenty of water: During cooler weather (40°F) a 1,500 lb. dairy cow producing 80 lb. of milk per day will drink an average of 25 gal. of water per day. The same cow will drink 33 gal. of water per day in hot weather (80°F). Cows that are producing more milk will need even more water. There must be at least 3" per cow in the pen of space along the water trough; this will decrease competition and ensure that all animals have access to clean water.
2. Shade: Studies have shown a 10% to 20% increase in milk production for cows offered shade in pasture versus those without access to shade. For high-producing, lactating cows this is essential, but don't forget the heifers and dry cows out on pasture.
3. Fans: Fans will help remove radiant heat. Choose fans that are 36" to 48" wide and place them 8' off the ground, 20' apart, at an angle of 15° to 25°

   downward toward the ground to offer continual air flow.

4. Sprinklers: Sprinklers over the feed alley, combined with fans, provide the best heat removal in most commercial barns, by using evaporation to help cool the cows. The sprinklers should be spaced at 8' off the ground, just under the fans, with a 180° spray and a 10 psi water flow, directed over the cows' backs. A good sequence is to have the sprinklers on for about 3 minutes out of 15 minutes.
5. Misters: In some drier climates, farms are able to use misters attached to fan systems over the beds to provide evaporative cooling of the air in the barn. The misters provide a fine spray that is designed to evaporate before settling on the beds. This evaporation will cool the air slightly.
6. Dietary changes: Decreasing concentrates and supplementing fats can increase the energy density of the diet while decreasing the heat produced by fermentation. Do not increase the fats above 6.5% of dry matter. Decreasing the forage content or feeding higher quality forages will also reduce the heat from fermentation.
7. Focus on fresh cows: During the summer months, fresh cows will be more susceptible to metritis, mastitis, ketosis, and other diseases because the cows will eat less during this critical period and their immune function will decrease. By monitoring the fresh cows closely, you can diagnose these problems earlier and address them more aggressively before they become critical.
8. Focus on the holding pen and milking parlor: One of the hottest places on the dairy farm is the holding pen, due to the high density of the cows, which does not allow them enough space to radiate heat. Cows need a minimum of 36 to 48 sq. ft. to prevent heat transfer between cows. When moving cows up to the holding pen, bring up smaller groups instead of a whole pen.
9. Don't add to the stress: Don't work cattle (moving, sorting, or transporting) or give vaccinations on very hot days. Anything that adds to the stress of the cattle - vaccinations certainly add stress to the immune system - can make the difference between a cow that can cope with her heat stress and a cow that is pushed over the edge into illness.
10. Tunnel ventilation with cooling cells: The most effective model for smaller farms is to use a combination of cooling cells and tunnel ventilation. This combination can decrease the temperature in the barn by up to 10° from the outside temperature.