As I made the rounds of producer meetings this past winter, one topic that I always tried to include in my presentations was emergency ventilation preparedness. Simply said, how are producers prepared to deal with electrical outages at production facilities?
To illustrate how serious this concern should be, I asked audience members for a show of hands of people who had experience with an electrical outage causing pig deaths, most often in grow/finish facilities. In every meeting, I had many hands raised, suggesting that our industry needs to do a better job of preventing such deaths.
First responders at sites where pig deaths have occurred all talk about a wall of heat and steam greeting them when they first open the facility’s door. When such deaths occur, producers, veterinarians and insurance agents often talk about suffocation. In fact, the pig deaths almost always occur due to excessive heat.
Indeed, today’s grow/finish pigs produce large amounts of heat, more so than prior generations of pigs. This increase is related to genetic, housing and nutritional advances that allow today’s pigs to have very high rates of lean deposition. For pigs over 200 pounds, this heat production may approach 1,000 Btu per hour. So, for a 1,000-head finishing room, this is the equivalent of four very large furnaces operating continuously.
This heat is dissipated from the pig as both latent and sensible heat. That means, in thermal-neutral conditions about two-thirds of the heat is released as sensible heat (air temperature) and one-third as latent heat (moisture vapor). The heat associated with moisture vapor comes from the pig’s lungs and skin, and from drying surfaces in the facility such as the floors.
In the event of an electrical failure, which cuts off the facility’s ventilation, pig heat production does not stop. The net result is that the temperature within the facility rises very rapidly — often faster than 1° F per minute.
As the air temperature in the facility rises, the non-ventilated air’s ability to hold the additional heat that the pigs produce declines. This means a higher percentage of that heat production must be converted to latent heat or water vapor.
In less than one hour for big pigs, the air becomes saturated with moisture, which means no more heat can be held there, and the air temperature approaches the skin temperature of 95° F. Again, the pigs are still continuing to produce heat, which means their core body temperatures will rise. Ultimately, pig death is due to core body temperatures climbing higher than 110° F, not due to high levels of carbon dioxide or a lack of oxygen.
If you ask producers who’ve been involved in these types of situations about the surviving pigs, they all comment that animals in the sick pen and/or runt pigs survived. Essentially, those pigs survived because their heat production rate was less than for the fast-growing pigs which died. By the time the poor-doing pigs’ core temperatures were climbing, enough pigs had already died that the room conditions were no longer changing at such a rapid rate.
To prevent the related pig deaths among late-finishing pigs, you have about 30 minutes from the time an electrical outage causes the ventilation system to fail to get some type of heat relief in place. For smaller, growing pigs, the time line is one hour.
Many production facilities in the United States are designed with magnetic curtain drops as protection devices. These are designed to open sidewall curtains within three to five minutes after a power failure occurs. Unfortunately, I have a computer file full of pictures taken at production sites where these devices, though present, are not connected. For contract growers, this would be a clear case of negligence and they risk liability for the pig deaths.
At other sites, producers rely on tractor-based, power-take-off-driven generators that must be manually connected to the electrical system when a failure occurs. My question to producers with this protection method is “do you have someone within 30 minutes of the site available 24/7 who is responsible for connecting the generator?” What happens when you or that person goes to the state basketball tournament or the church dinner in the next community or any number of events? Bottomline: Can you have the emergency system operating in sufficient time to prevent pig deaths? If not, it’s not a worthy system and you have to find another alternative.
I do hope that we all make enough progress regarding emergency heat relief awareness that next winter, when I ask for a show of hands related to such pig deaths, it’s only a memory and it’s not a commentary on our current conditions.