Reduced Night-time Temperatures in Pig Nurseries

Research at Michigan State University suggests that producers adopting a strategy of reducing night-time temperature are more closely aligning their management with the pig's preferences as well as achieving cost savings. Gerald May (MSU Extension Educator) and Ronald O. Bates (State Swine Specialist) report the latest results in 'MSU Pork Quarterly'.
calendar icon 7 November 2013
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Pork producers strive to raise pigs efficiently and within an environment that is considered comfortable and animal friendly. One opportunity for increasing the efficiency of pork production, while at the same increasing the comfort level of the pigs, is through reduced night-time temperatures during the nursery phase of production.

The feasibility of reducing the night-time temperature in pig nurseries was recognised in the early 1980s, when Dr Stanley Curtis (Curtis and Morris, 1982) reported if given the opportunity, pigs would choose to reduce their thermal environment through the evening and night-time hours. This diurnal temperature preference by pigs was reaffirmed by Bench and Gonyou (2007) at the Prairie Swine Center.

In a trial to measure the impact of reduced night-time temperatures (RNT) on pig performance, Brumm et al. (1985) reported no differences in feed efficiency and slight improvements in average daily gain (ADG) and average daily feed intake (ADF) for pigs raised in rooms with RNT during the nursery phase. Brumm et al. also reported the RNT pigs did show a slight increase in fall-backs and mortalities that were removed from the trial, 2.6 per cent fall-backs and mortalities for the RNT versus 0.5 per cent for the controls.

In Brumm’s experiment, temperature in the control room was set at a consistent 89°F for the first seven days then decrease 4°F per week for the duration of the trial. Temperature in the RNT room was reduced from 7:00pm to 7:00am to 80°F the first three days post weaning, 70°F the next four days, and then reduced 2°F per week thereafter.

Subsequent trials (Shelton and Brumm, 1988, and Nienaber and Hahn, 1989) reported no adverse effects including mortalities and fallbacks, of RNT but the improvement in average daily gain and average daily feed intake shown in Brumm’s 1985 report was not consistent across experiments. In both subsequent trials, the RNT pigs were provided a five- to seven-day acclimation period where temperatures during the nighttime hours were maintained at 89°F before implementing a RNT regime.

Since those early trials with RNT, genetics have changed, pigs have become leaner and nursery design has been improved. In an effort to reevaluate the impact of RNT, a team of researchers from across the US, led by Lee Johnston of the University of Minnesota, conducted trials using two different RNT regimes. In both trials, the control room was set at 89°F when the pigs first entered then reduced 4°F each week post weaning. In trial 1, the RNT room was set at a constant 89°F for the first seven days then reduced 11°F during the nighttime hours (7:00pm to 7:00am).

Treatments in trial 2 were similar to those in trial 1 except the reduced nighttime temperature was initiated on day 5 rather than day 7 and the nighttime temperature was reduced 16°F rather than the 11°F implemented in trial 1. Since Johnston et al. (2013) reported that no differences were observed in average daily gain, average daily feed intake, feed efficiency or mortality in both trials, only the results from trial 2 are presented and discussed here.

In trial 2, four nurseries were utilised in the experiment, one each in Minnesota, Missouri, South Dakota and Ohio. Results from nine control rooms (2,122 pigs) and 10 RNT rooms (2,176 pigs) were included in the analysis. Pig flow depended on the normal operating procedures for the each participating nursery. Pig age when placed on trial ranged from 16 to 22 days and each trial lasted from 28 to 42 days.

Figure 1 provides the average day time and night-time temperature of the control and RNT for the four participating nurseries. The average night-time temperature in the RNT room was significantly cooler than the control room temperature but the difference, as indicated in the graph, decreased as the pigs matured. The increased body heat of larger pigs compensated for the reduced supplemental heat. The researchers reported that after day 10 the RNT rooms did not cool down to the reduced furnace setting meaning that after day 10, there was no supplemental heat used during the night-time hours in those rooms.

Figure 1. Average day- and night-time room temperatures for control and RNT treatments

Table 1 provides the performance for all pigs in trial 2. The researchers report no differences in pig performance, days sick pigs were treated and piglet mortality due to reduced nightly temperature.

The energy savings from RNT reported by the researchers is presented in Table 2. Thirty per cent less propane and 20 per cent less electricity were used in the RNT rooms in comparison to the energy used in the control rooms.

Extending the propane and electricity savings in Table 2, Table 3 illustrates a potential $1.70 per pig economic savings from the RNT strategy using estimated 2013 prices for propane and electricity. The nursery fill dates monitored in this trial ranged from November to March with the majority of the fill dates being in December, January and February, a period of high energy requirements. The energy savings reported should not be assumed as annual reduction in fuel and electricity needs but rather as an indication of the potential savings during times of high energy usage.

To implement this strategy the nursery manager needs to reduce the heater ON setting, or turn down (or increase) the heater ON setting from set-point, during the nighttime hours. The goal is allow the room temperature to gradually decrease to the desired RNT setting. Do not cool the room to the RNT setting by adjusting the temperature set-point. Adjusting the room temperature set point would result in a sudden cooling of the room, chill the pigs, waste energy and should be avoided.

For some nurseries, adopting the RNT strategy will require either management changes or equipment upgrades. Ventilation equipment representatives are reporting some of the new ventilation and temperature controllers have the capability to automatically adjust the heater ON setting based on time of day.

Nurseries with earlier technology will be more challenging. Brumm reported that in their early trials, they used a second controller with a reduced heater ON setting along with a time clock to switch between the controller for the day-time settings and the RNT settings. Others may want to try the RNT by simply manually adjusting the heater ON setting each morning and night. The Bench and Ganyou (2007) report showed pigs preferred a RNT starting at about 7:00pm and an increased room temperature starting at about 7:00am. Nursery managers implementing the RNT strategy by manually adjusting the heater on setting each day should avoid setting the RNT too early in the afternoon (4:00 to 5:00pm) when the pigs are still active.

Research has shown that if given the opportunity to adjust their thermal environment, pigs will choose a reduced night-time temperature.

Producers adopting the RNT strategy are more closely aligning their management with the known preferences of the pig and thereby increasing the well-being of the animal.

RNT will also result in a significant cost-savings to the producer.

At a time when producers are seeking both production cost-savings and management practices that closely match the needs of the animal, RNT should be applicable in the well managed pig nursery.


Bench, C.J. and H.W. Gonyou. 2007. Temperature preference of piglets weaned at 12–14 days of age. Can. J. Anim. Sci. 87:299-302.

Brumm, M.C., D.P. Shelton and R.K. Johnson. 1985. Reduced nocturnal temperatures for early weaned pigs. J. Anim. Sci. 61:552-558.

Curtris, S.E. and G.L. Morris. 1982. Operant supplemental heat in swine nurseries. Proceedings of the second international livestock environment symposium. Amer. Soc. of Ag. Eng. St. Joseph, MI.

Johnston, L.J., M.C. Brumm, S.J. Moeller, S. Pohl, M.C. Shannon and R.C. Thaler. 2013. Effects of nocturnal temperature on pig performance and energy consumption in swine nursery rooms. J. Anim. Sci. doi:10.2527/jas.2012-5824.

Nienaber, J.A. and G.L. Hahn. 1989. Cool nighttime temperature and weaning age effects on 3 to 10 Week old pigs. Transactions of the ASAE. 32(2):691-695.

Shelton, D.P. and M.C. Brumm. 1988. Reduced nocturnal temperatures in a swine nursery - a modified regimen. Transactions of the ASAE. Vol. 31(3):888-891.

November 2013

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