Separate guidance has also been prepared under the Integrated Pollution Prevention and Control ( IPPC ) Directive to reduce a range of polluting emissions from large pig and poultry units . The `` Reference Document on Best Available Techniques ( BAT ) for Intensive Rearing of Poultry and Pigs '' , the BREF ( BAT reference ) document , may be found at : http : //eippcb.jrc.es/pages/FAbout.htm ) .