5 September 1997


There is still too much dust and noxious gas in pig buildings, increasing disease and reducing efficiency.

Michael Gaisford reports

CURRENT disease costs related to poor pig environment amount to £43m a year, out of total annual disease bill for the UK pig industry of £135m. This £43m – estimated by the British Pig Veterinary Society – excludes a further £2m incurred through staff illnesses, and staff recruitment and retention difficulties.

At Silsoe Research Institute, Beds, scientists have completed a survey of temperatures, humidity levels, dust, ammonia and other airborne toxins in 330 intensive livestock buildings in Britain, Denmark, Germany and Holland.

Measurements taken in both summer and winter, showed that maximum ventilation capacity was often inadequate and ventilation controls did not maintain target temperatures effectively. As a result significant levels of airborne endotoxins were recorded.

In many of the pig buildings, dust and ammonia levels exceeded animal welfare and health and safety recommendations.

By far the worst dust levels – well exceeding safe levels for pig health and welfare recommendations – were recorded in British straw-based sow houses.

The survey funded by EU and MAFF was co-ordinated at SRI by Roger Phillips.

"The survey has identified a clear need to improve air quality in many pig buildings. There are a number of techniques for doing this, but they are expensive. More research is required to develop practical systems to prevent emissions, or clean the air in situ," comments Dr Phillips.

New priorities

SRI has been consulting the British pig industry about new research priorities.

"Industry deemed that the highest priority for research work was hybrid ventilation systems which combine both natural and fan ventilation systems," says Dr Phillips.

After this industry favoured work on the integration of environmental control into management systems, followed closely by work on abatement techniques for pollutants within pig buildings.

Research on the biological response of pigs to pollutants, financial costs and benefits of aerial pollutant control and development of better sensors for aerial pollutants, were also high on the list of industry requests.

Aerial pollutants in pig buildings were listed as dust, ammonia, hydrogen sulphide, methane, nitrous oxide, carbon dioxide in descending order of importance.

"We are now formulating research ideas to put to MAFF and industry, taking into consideration the EU directive, Integrated Pollution Prevention and Control which is scheduled to be implemented in 1999," says Dr Adam Robertson, of SRIs Bio-Engineering Division.

Dr Robertson says that this new directive will apply initially to all new large installations with over 750 sows or 2000 places for pigs over 30kg, and eventually to all such existing pig units, covering an estimated 435 farms.

Many details have yet to be finalised, and MAFF is currently circulating a consultation paper.

Ammonia issue

"In terms of aerial pollution, ammonia emissions will be the main issue," predicts Dr Robertson.

"In our research we clearly need to look at better ventilation and pollutant abatement techniques.

"The Danes and the Canadians are already working on reducing dust levels by spraying oil into the air inside pig buildings, and we need to take a much closer look at all possible economic ways of reducing both dust and ammonia levels in intensive livestock buildings," says Dr Robertson.

He says that current estimates suggest the British pig industry is discharging some 22,000t a year of ammonia nitrogen into the atmosphere. One of the research priorities is to reduce this discharge, which contributes to soil acidification and affects natural ecosystems by excess nitrogen input.

Other reasons given by Dr Robertson for improving pig building environments, include making our pig industry more competitive with imports by satisfying retailer requirements. &#42

Right:SRIs Adam Robertson says that research could play a leading role in farm assurance by ensuring that pigmeat is produced in healthier and more welfare friendly conditions.

Left:Dummy pigs are used in Silsoe Research Institutes mock-up of a pig building where the effects of different ventilation settings on dust and gases can be measured.

Research at the Silsoe Research Institute, covers productivity, health, and welfare of pigs and stockmen in buildings, and of pigs in transit between farms and en route to abattoirs.

Facilities include:

&#8226 A mock-up of part of a full size intensive livestock building with a high speed inlet jet ventilation system. This allows different levels of dust and noxious gases to be introduced and measured under different ventilation, temperature and humidity conditions with varying pig stocking densities.

&#8226 A unique chamber where the behaviour of pigs can be studied under different atmospheric pollutants in a series of eight pens.

&#8226 Animal transporter vehicles where fan ventilation systems are being developed to improve the environment of pigs on the move, and when loads of pigs are stuck in traffic jams in hot weather conditions.

&#8226 A video image analysis arrangement which assesses the weight and growth rate of pigs while they are feeding without having to handle and physically weigh the pigs.


&#8226 Development of hybrid ventilation systems.

&#8226 Spraying oil into pig buildings.

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