range 3.2–8.7 ppm and 4.4–10.8 ppm in the shower treatment and control, respectively. Consequently, mean ammonia emissions were lower in the shower treatment (3.0–5.1g per pig per day) than in the con- trol (4.2–10.0g per pig per day), with greater differences be- tween the treatments at the end of the growing period. The differences were significant in all four measuring periods dur- ing the batch. The shower system reduced ammonia emis- sions during summer by 45%.
Cooling can significantly reduce pen fouling.
fouling scoring revealed that fouling increased throughout the measuring periods in both the shower and control rooms, but that overall pen fouling was significantly less in the show- er treatment than in the control. Average ammonia concentration in outlet air varied in the
Figure 1 - Results of the shower treatment: decreased lying on slatted floor, improved pen hygiene and reduced ammonia emissions.
40 50
10 20 30
0 Week 3-4
2,5 3
2 1,5
0,5 1
0 Week 3-4
10 12
6 8
0 2 4
Week 3-4 Week 6-7 Week 9-10 Week 12-13 Week 6-7 Week 9-10 Week 12-13 Control treatment Shower treament Week 6-7 Week 9-10 Week 12-13 Control treatment Shower treament
Control treatment Shower treament
Increased air velocity In the experiment with altered air velocity in the lying area, the treatment with readjusted air inlets and maximum 1.0 m/s showed a positive effect compared with the control. However, the difference obtained was not as large as that between shower treatment and control. The pigs were observed lying significantly more in the area with increased air velocity and less on the slatted floor. Pen fouling was significantly reduced. Measured ammonia concentration in outlet air varied in the range 3.7–11.0 ppm and 3.9–14.4 ppm in the readjusted air inlet treatment and control, respectively. Mean ammonia emissions during the measuring periods increased from 3.4g to 6.6g per pig per day in the treatment with readjusted air inlets and from 3.3g to 8.4g per pig per day in the control. A significant reduction in emissions in the readjusted air inlet treatment was found, but only in late stages of the batches. During the late period of the batches the ammonia emissions were reduced by 21%. For an entire batch, increased air veloc- ity on the lying area reduced ammonia emissions during summer by 13%.
Future developments One disadvantage with the shower technique is of course the water consumption, which increased by 20–35%. However, the settings and control of the shower system can be im- proved. The PigSys project has provided the tools needed for refinement of the technique controlling pig behaviour and house environment, using a decision support system (DSS), computer vision and various sensors. Cooling the pigs with forced convection during periods with high ambient temperatures is a well-known method used in pig houses. However, the potential for using higher air velocity in pig houses as a measure to cool the pigs has not yet been fully utilised. In future work, cooling/heating of the lying area may be tested, as well as the possible addition of various odours and light to guide the pigs to suitable behaviour in the housing system.
Authors Jeppsson and Olsson are attached to the Swedish Uni- versity of Agricultural Sciences (SLU) and Nasirahmadi to the University of Kassel, Germany. This research was part of the EU project PigSys; the website
www.pigsys.eu shares more details about the set-up of the investigation.
▶ PIG PROGRESS | Volume 37, No. 3, 2021 17
Ammonia emission, g pig–1 days–1
Pen fouling scoring
Lying on slatted floor, %
PHOTO: KNUT-HÅKAN JEPPSSON
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