This Test Guideline describes a standardised method to examine the transformation of chemicals in pig and cattle liquid manure under anaerobic conditions. The experiments are performed to determine the rate of transformation of the test chemical, the identity and rates of formation and decline of transformation products and residues). Such studies are relevant for chemicals that are administered to housed animals and are subsequently excreted (e.g. veterinary medicinal products or feed additives) or for chemicals that are applied in buildings for livestock and may also enter the manure collected from these animal housings (e.g. biocides). Pesticides may also be introduced into manure via contaminated animal feed.