Dutch sties for fattening pigs and sows are often not suitable for the application of partial underfloor extraction to improve the air quality in the pigsty, a system used in Denmark. Researchers at Wageningen UR Livestock Research expect that the manner of ventilation (ground channel ventilation) and the large proportion of solid, non-ventilated floor is the cause of this.
Good air quality in pigsties
Pigsties are generally equipped with air scrubbers which remove ammonia, odours and fine particulates from the outgoing air. The outgoing air is therefore cleaned. However, this does nothing to improve the air quality inside the stall. Good air quality inside the pigsties is becoming increasingly important, for instance due to the effects on the health of the pig farmer and on the welfare and health of the animals that have to live in this housing 24 hours a day. Research has been under way in Denmark for a number of years already into the localised extraction and cleaning of the air. In this system, a proportion of the air (approx. 10 to 20% of the maximum capacity) is extracted from under the slatted floors and cleaned, while the rest of the air is extracted via the ceiling. In Denmark, this resulted in a reduction in ammonia emissions of 50 to 70%.
The research was performed at VIC Sterksel in housing for fattening pigs and gestating sows. Just as in the case of an extraction fan above a stove, part of the contaminated air just above the manure, below the slatted floor, is extracted. Each of the two testing departments for fattening pigs had a control department exactly like the other except for the air extraction. The system of underfloor extraction was built into the department with gestating sows, and switched on and off alternately.
The objective of extracting large quantities of ammonia and other contaminants (odours and fine particulates) in small quantities of air by means of partial underfloor extraction was not achieved in this study. In the case of the fattening pigs, the percentage of extracted ammonia in the underfloor-extracted air was approximately the same as the percentage of air extracted under the slatted floor (42% ammonia in 40% air). In the case of the sows, this percentage was slightly higher (44% ammonia in 31% air).
New sty concepts are required in order to make underfloor extraction a promising technological development in the Netherlands. In order to produce favourable, effective designs, the advice is to use air flow models in advance.
This research was performed by Wageningen UR Livestock Research, commissioned and financed by the Ministry of Economic Affairs. Other cooperating parties in this research were Aarhus University, the University of Copenhagen, the Danish Agriculture & Food Council, the Danish company Skov A/S and the Dutch company JOVAS Agro International B.V.