It’s 19 degrees with snow on the ground as I write this article, and heat and flies are not the first thing on producer’s minds. However, as we all know, that can change quickly in the Midwest. Let’s review a few things to help prepare for summer heat and flies. Keeping calves cool and comfortable, and minimizing flies are the two main goals for the summer season.

If your calves are in a group housing facility, the two main goals are good ventilation and dry bedding. At 70 degrees or above, curtains should all be wide open and there should be up to 40 air exchanges per hour. This can be achieved with a positive pressure tube ventilation system. These tubes are separate from the minimum ventilation tubes for winter. They are designed to drive high-velocity air down over the calves, with a goal of air movement of 200 ft per minute over the calves in order to provide heat abatement for the calf. Cross ventilation barns should seek the same number of air exchanges per hour and airspeed at calf level.

If your calves are in calf huts, at 70 degrees or above all vents on the hut should be open. To provide additional air flow for the calf, the back of the hut should be propped up with a 6 to 8-inch block or tire. Shade cloth over the top of huts or placing these huts where there is shade, and spacing the huts farther apart is also helpful. Beware of semi-transparent huts that can have a green-house effect and result in extremely high temperatures in these huts that can be fatal to calves. This type of hut must have full shade.

Having drinking water available to calves at all times is extremely important. Besides their regular feedings of milk, calves should have clean, fresh, water 24/7. Develop a routine that ensures calves have water that is clean and the bucket does not have a biofilm on it or stale feed in the bottom of the bucket. Dump and replace with fresh water regularly.

Flies and Health

Important to both fly control and respiratory health is clean dry bedding. Flies love to reproduce in wet bedding and the ammonia can cause respiratory problems. Straw bedding is great for winter bedding but in summer, saw dust or other such material is preferred. Regardless of what you use, keeping it dry will reduce flies and keep calves healthier. You can do the “knee test” if you’re not sure how dry it is. If you drop to your knees and they get moist or wet, you need more bedding.

There are many fly control products on the market. Clarifly in the milk passes through the calf and prevents fly eggs from hatching in the manure. These pass thru products can also be included in calf starter. Numerous sprays for spraying the calf and the hut are available. Be sure the one you use is safe for calves. Pyrethrin products are generally safe. Fly bait stations in areas around the confined calf are also effective. Weed control around huts and calf buildings will also reduce painful biting stable flies which like to hide in weeds during night hours.

Last but not least, keep in mind that energy requirements of the diet increase for calves in hot weather as they increase respiration to help dissipate heat.