Prioritize cow cooling efforts
It’s the beginning of summer and the living is easy. Unless, of course, you’re a cow.
High milk production plus even moderate temperatures (in the 70°s) equal the beginning of heat stress, says Jim Spain, a dairy specialist at the University of Missouri.
If you are limited in the amount of cow cooling you can offer, Spain offers the following priorities:
- If you can do cooling in no other place, at least do so in the holding pen—and every time cows come through when the temperature-humidity index exceeds 73. That will ensure cows will be cooled at least twice daily (three times if you milk that often). The holding pen is also where cows can experience the most heat stress each day as they crowd together and share their body heat.
- Leave freestall fans running overnight. Cows reach peak core body temperatures between 8 p.m. and 2 a.m. "It takes four hours of fan cooling time to bring those temperatures down. So why do we turn fans off atnight?" Spain asks.
- There’s a belief that if you place fans at the feedbunk, cows will stand at the bunk and eat more. Spain says cows will stand at the bunk longer under fans, especially if the freestalls don’t have fans. But research shows that they won’t eat any more. All they’re doing is standing more, which only leads to more lameness.
- If you have to prioritize where you place fans, such as a choice between the feed line and freestall beds, place the fans over the beds. The reason: Cows spend—or should spend—more time resting in the freestalls than standing at the feedbunk.
- Position fans so that they blow air over the entire cow. If you simply place fans down the center of the freestalls in head-to-head rows, you’ll only cool the cows’ heads and lose the cooling effect on the cows’ bodies. The cow’s large body mass is where you need to direct cooling.
- Cool your close-up cows because they are especially susceptible to heat stress. "The fetus produces substantial heat due to the very high metabolism rate associated with fetal tissue growth and development," Spain says.
One of the best ways to cool the close-up cows is to run them into the holding pen during down times. It often has the best fans on the farm, and if the pen isn’t crowded, can provide substantial relief.
At Missouri, researchers sprinkled close-up cows twice a day—7 a.m. and 7 p.m.—until their skins were wet. Then they ran fans for at least an hour. Milk production was 5 lb. per day higher for the first six weeks after calving for these cooled cows. Other research has shown cooled close-up cows breed back sooner with fewer services per conception.
If you can’t soak cows or provide fans, try to at least provide shade for dry cows, Spain adds.
- Finally, calves that are in hutches need shade cloth over the hutches. Research at Missouri shows temperatures in a hutch can be 10° higher on the inner surface of the hutch if it is not protected by shade. "Rectal temperatures and respiration rates of the calves in the shaded hutches was significantly lower," he says.