Tannins are a very complex group of plant anti-nutritional compounds.
Their major negative effect results from either direct inhibition of digestive enzymes or formation of indigestible complexes with feed and endogenous proteins. These PEGs are used to alleviate adverse effects of tannins. How tannin-PEG complexes and the free PEG behave in the environment and what effect these have on the ecology are not known. The objective of the present study is to investigate degradation of PEG and its complexes with tannins using aerobic and anaerobic fermenters. Our studies have shown that polyethylene glycol is completely degraded in an aerobic fermenter in about 2 days and in an anaerobic fermenter in 12 days.