MANAGEMENT ▶▶▶
Cooling down for more hygiene, less ammonia
Keeping pigs cool in times of heat stress has a positive effect on their fouling behaviour and subsequently on the formation of ammonia. In Sweden, researchers tested two methods of cooling finisher pig houses with partly slatted floors and measured the effect on fouling behaviour.
Example of a shower treat- ment for pigs.
PHOTO: KNUT-HÅKAN JEPPSSON
BY KNUT-HÅKAN JEPPSSON, ANNE-CHARLOTTE OLSSON AND ABOZAR NASIRAHMADI P
artly slatted pens have a solid floor for pigs to lie on and a permeable slatted floor as a dunging area for the pigs. This design enables allocation of some lit- ter as enrichment. Use of litter reduces problems
with tail biting when rearing undocked growing/finishing pigs and is considered to improve pig welfare. Pigs also prefer a solid lying area with litter under thermo- neutral environmental conditions. If the solid pen area is kept clean, pig houses with a partly slatted floor system in the pens have around 25% lower NH3
a fully slatted floor system. That is explained by the smaller emitting surface area.
Pen fouling However, during summer periods with high ambient tempera- tures, pen fouling can occur. Pen fouling leads to impaired hy- giene and air quality, increased NH3
emissions and extra work
trying to keep the pen clean. Pen fouling problems have in- creased in Sweden in recent decades. Suggested explanations are that modern pig genotypes are more sensitive to climate change–related heat stress and prolonged periods with high ambient temperatures inside pig buildings during summer months. Measures to reduce the problem are needed. Two possible methods for cooling pigs in existing buildings, tested within the research project PigSys, are described in this article. Pen fouling may depend on many factors. In hot conditions, the main causes are unfavourable thermal climate for the pigs, in combination with restricted space allowance. To cope with this situation the pigs change their lying posture, in- creasingly lie on the slatted floor since it is the coolest place in the pen, excrete on the solid floor and start to wallow.
Pig cooling measures Two different measures for cooling housed pigs during very
16 ▶ PIG PROGRESS | Volume 37, No. 3, 2021 emissions than houses with
warm summer weather (2018 and 2019) were tested in the study. These were: • Showering above the slatted area; and • Increasing the air velocity on the lying area by readjusting the ceiling inlets (from 35 to 75 degrees relative to the ceiling). The study was performed in one grow-finishing pig house on an integrated commercial pig farm in southern Sweden with 480 sows and 3,600 growing-finishing places. The grow-fin- ishing pig house had ten identical rooms, with 16 partly slatted pens in each. Each pen could accommodate nine to 13 finishing pigs and had a floor that was 70% solid concrete and 30% concrete slats. In different batches, showering or readjusted ceiling inlet treatment was compared with an untreated control. In the shower treatment, the slatted area in each pen was showered with water controlled by the ventilation system. Showering started when the air temperature in the com- partment exceeded the target temperature by more than 0.5°C. In the treatment with readjusted ceiling inlets, the maxi- mum air velocity on the lying area was increased from about 0.5 m/s to 1.0 m/s when the temperature of the inlet air ex- ceeded a certain limit value. Readjusting the ceiling inlets changed both the air flow pattern and the air velocity at max- imum ventilation in different areas of the pens. With the larg- er opening angle, the inlet air was aimed directly down into the animal lying area, increasing air velocity in this area.
Shower treatment In the control rooms, with no cooling, the pigs had started to lie on the slatted floor already in week 6 of the batch, weigh- ing about 40kg, and the percentage lying on the slatted area increased throughout the batch. In comparison with control pigs, the pigs in the shower treatment used the lying area more, and the slatted area much less, when lying. No differ- ence in pig activity was seen between the treatments. Pen
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