Reducing Nocturnal Temps Saves Energy and Increases Daily Gain

By Sarah Watson, Livestock Editor
Thursday, December 20, 2007 1:19 PM CST

With the ever increasing energy prices over the last year, hog producers have been looking at ways of cutting energy costs. A study conducted by the University of Missouri not only cut energy costs, but increased average daily gain by incorporating reduced nocturnal temperatures in the nursery.

The first studies of reduced nocturnal temperatures (RNT) were conducted in the late 70s and early 80s during a period of increased energy costs, and the recent spike in energy costs also made researchers take another look at the energy conservation technique. Researchers also wanted to check the impact of RNT on feed efficiency and feed gain.

“The thought is that with the genetic changes in efficiencies, that our buildings might be running just a little warmer than they need to be,” says Joe Zulovich, University of Missouri Extension agriculture engineer. “Energy prices have taken a jump, propane is about double what it was three years ago.”

The nursery phase of hog production requires the highest temperatures and the study examined this phase only.

The 28 day nursery study was conducted at the University of Missouri from January to March 2007. Two hundred forty nursery pigs, 18 days old, weighing 12.4 pounds were allotted to environmental treatments. Pigs were tested before the experiment to determine health status, and tests were negative for PRRS, positive for porcine circovirus 1, N1N1 influenza and H3N2 influenza.

No scouring was observed during the 28 days indicating the pigs were in high health. Pigs did not seem chilled by the reduced temps as piling or other indications were not observed when pigs were exposed to the reduced nocturnal temperatures, according to Zulovich.

Energy savings with RNT were 8 percent for electricity and 18 percent on natural gas n which results in an overall savings per pig of $0.38.

Along with the energy savings, Zulovich recorded an increase in average daily gain (ADG) of 1.21 pounds per day and increased feed intake of 2.1 pounds per day compared to earlier studies results of 1.13 pounds per day and 1.9 pounds per day, respectively.

The answers to the increase ADG may be found in genetics and the temperature.

“The other thing is that when pigs feel a little chilled that may be an appetite enhancer,” he says. “It’s not really known just exactly why.”

A higher ADG is an added bonus to the energy savings.

“When you think about it, pigs have changed in the last 25 years, but our building operational management recommendations have pretty much stayed the same as they’ve been for the last 20, 25 years,” he says.

Even the recommendations for RNT haven’t changed a whole lot since the initial trials in the 80s, he explained.

When implementing RNT the temperature is dropped up to 10 degrees from the daytime temperature. During the first week the temperature is unchanged, and is dropped by a couple degrees every week after.

“Most nursery pigs are going to be somewhere in the 84-88 degrees for air temperature at weaning,” he says. “Depending upon management preferences you’d want to get down to 70-75 degrees.”

Some producers will hold temperatures the first week like recommended, but drop two degrees hold the second week, hold and drop two more degrees, or will drop a few degrees every four or five days. It depends on the management style, Zulovich says.

“The other thing is, reduced nocturnal is not implemented right away post weaning,” he explains. “Don’t do it right away in those first two weeks.”

Waiting to reduce temperatures allows the pigs address weaning stress without the added strain of cooler temperatures.

“You really don’t want to be reducing right away,” he explains. “When we redid the work, we left them alone for the first couple of weeks.”

Zulovich doesn’t believe that there are very many producers utilizing this practice right now.

“It’s not something that’s common knowledge,” he says.

Animals need to be healthy for implementation of RNT.

“For the most part, this is a management strategy you want to use only when your pigs are healthy,” he says. “If you’re dealing with pigs that have been sick and they’re on active treatment this is something you might not want to do. When you don’t feel good you don’t really want to be chilled.”

Overall it’s a win-win situation for producers with increased ADG and a significant reduction in energy costs.

“It might be a methodology to implement to reduce your energy use and reduce your heating cost,” he says. “I don’t have any reservations of saying ‘no you don’t want to do that’.”

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