This week has been the hottest week for pigs in production facilities in the upper Midwest for this summer. While I wrote last week about the sale weight impacts of summer heat, I did not address many of the common mistakes producers and contract growers make in applying management strategies to keep pigs cool.

On Wednesday I was in the wean-finish barns of a modest sized production system. All of these barns house 2450 pigs per room and are generally 70 ft wide. At all of the sites, there were 2 rows of ‘misters’, whether the facility was a large pen design or small pen design.

At the last stop of the day we spent time observing pig behavior as the ‘misters’ cycled on and off. At sites earlier in the day we had talked about options to increase the area of coverage in a pen, but at this site with market ready pigs the lack of coverage was obvious.

In the barn it occurred to me that we always had 2 rows of ‘misters’ when our barns were 40 ft wide. Now 70 ft wide facilities are common and the barns in this system were still only providing 2 rows of misters. With a ‘mister’ above every pen they’ve gone from providing a one ‘mister’ per 25-27 pigs to providing one ‘mister’ per 45-47 pigs. As we watched pigs fight to get under the ‘mister’ it became obvious where the production limit in the barn was this week.

By now you should have noted that I have quotation marks around ‘mister’. In the barns yesterday the nozzles installed put out a semi-fine mist. Even with a 2 minute ON time, a majority of the pigs that could access the wet area of the pen only had the hair on their bodies wet. As we went through pens and rubbed pigs, many of the pigs that were under the ‘misters’ had a skin surface that wasn’t very wet.

The goal of wetting the pigs should be to get the water down on the skin, not setting on the hairs of the pig above the skin surface. This takes large droplet sizes. Data from Kansas State University more than 30 years ago demonstrated that while ‘misting’ pigs is better than doing nothing, it is not nearly as effective as ensuring the water reaches the skin surface so that the pig cools by evaporating the water.

Our experiences yesterday reconfirmed the need to install the correct equipment in grow-finish facilities to assist the pig with cooling during days and nights such as we’re experiencing this week. Strive for 50- 60% pen coverage with your water additions and make the droplet size large enough to reach the skin surface. While the mist may ‘feel good’ to us, our concern should be the appropriate conditions to help the pig in the housing arena we provide.

You also need to review your controller settings. In many of the production facilities yesterday the controllers were set to turn off the water additions at 10 pm and begin wetting again at 6 am. Barns are still very hot at 10 pm. I generally recommend wetting pigs until 1-2 am. You don’t need to start at 6 am as that is when the daily lows occur for air temperature. Again – the cooling mechanisms we provide for growing pigs need to match the conditions and timing of when the heat relief is needed.