As electricity, propane and natural gas costs all jumped dramatically this past year, you are no doubt looking for ways to cut utility costs. Since the nursery stage requires the highest temperatures, it makes sense that it would be the first place to lower temperature. Research shows that nighttime nursery temperatures could be reduced without depressing pig performance. However, that reesearch was done in the 1980s, when pigs where weaned at 28 days old. 

Today, pigs are weaned at 17 to 21 days old, and they are a totally different animal physiologically than those weaned at 28 days. So, the NCERA-89 Committee on Swine Management organized a research trial, funded by the National Pork Board, to determine if nighttime temperatures for pigs weaned at 17 to 21 days could be reduced without affecting growth performance. Researchers also measured energy utilization for temperature control to see if reduced nighttime temperatures lowered utility costs.

The two treatments considered were normal nursery temperatures, known as the controls, and reduced nocturnal temperature, known as RNT. Initial temperature for the control setting was 86˚F, which was then reduced 3.6˚F weekly through the nursery phase. For RNT, starting on the seventh day after weaning, nocturnal temperature was reduced 10˚F from control levels between 9 p.m. and 7 a.m. Control temperatures returned from 7 a.m. to 9 p.m. There were four experiment stations (Minnesota, Missouri, South Dakota and Nebraska) involved with two replicates per station.  At arrival, 1,258 pigs were ear tagged, weighed and assigned to treatments on the basis of sex and arrival weight so that sex ratio, weight and variation coeffficient were similar among pens.

Pigs were weighed weekly during the nursery phase to determine weight gain and feed efficiency.  Utility usage was recorded weekly for each nursery room, and nursery treatments were switched between rooms between trials 1 and 2. Standard nursery nutrition programs were followed at each institution, but they were not uniform among institutions. However, nutrition programs within a station were uniform across control and RNT treatments.

The results are for data collected in Minnesota, Missouri and Nebraska. Data from South Dakota was not included because barn design confounded the results. Nursery average daily gain (0.95 pounds per day), average daily feed intake (1.36 pounds per day) and feed/gain (1.46) were identical for the control and RNT pigs. Therefore, even pigs weaned younger than 21 days old (13.6-pound birth weight) can compensate for reduced nighttime temperatures after one week in the nursery without adversely affecting growth performance.

When looking at numeric means, heating-fuel use (BTU per pig) was reduced 17.4 percent and kilowatt-hour per pig was reduced 10.7 percent for the pigs in the RNT treatment. Using $2 per gallon for heating-fuel price and 8 cents per kilowatt-hour, this equates to a savings of $1.55 per pig in heating fuel and 5 cents per pig in electricity. This produced a total saving of $1.60 per pig, averaged across the three stations.

There was a significant location effect for BTU and kilowatt-hour usage. Based on this research, you can save a substantial amount of money through reduced propane and electrical costs by reducing nighttime temperature beginning the second week after weaning for “early weaned” pigs (13.6 pounds) without affecting growth performance.

However, remember that the temperature displayed on a thermometer or thermostat is seldom the temperature that the pig feels — that would be the effective environmental temperature, and it’s affected by many external factors. Higher ventilation rates, poor wall insulation, unplanned openings and drafts, wet surfaces and high humidity, as well as concrete or metal flooring will make the pig feel colder than the thermostat indicates. 

For example, a draft of 40 feet per minute (0.45 mph) reduces a pig’s EET by 7°F. You need to look at the thermometer as a starting place. Then make adjustments to the pigs’ environment based on the simple animal-husbandry skill of watching what the pig is telling you. If the pigs are piling during the day, the EET is too low regardless of what the thermostat says.

Reduced nocturnal temperatures can work well in the nursery, but you need to adjust the temperatures based on what the pigs tell you within your own operation.


Reducing Nocturnal Temperature Doesn’t Have to Reduce Performance

The treatments responded the same way at each location for the criteria measured, so only main effects are shown here. There were no statistical differences in BTU or kilowatt-hour usage between treatments. However, several factors could explain this. First, the lack of treatment effect could have been due to the large standard error associated with these two variables. Secondly, with only six replicates per treatment for energy consumption data, there might not have been enough replicates to detect any differences. 


The Savings Add Up

As a whole, there was a significant location affect in BTU and kilowatt-hour usage.

There was no difference in BTU usage between the control and RNT rooms in the Nebraska nurseries — it appears there was a problem with the heater’s monitoring system. However, there was still a reduction in electricity usage due to the RNT in that nursery. If the Nebraska data is omitted and just the Minnesota and Missouri data are averaged, RNT resulted in a heating savings of $2.33 per pig and an electricity savings of 6 cents per pig, for a total utility savings of $2.39 per pig.