• Ascorbic acid oxidase: oxidize ascorbic acid to dehydroascorbic acid
• Thiaminases: are enzmyes found in a few plants and the raw flesh and viscera
of certain fish and shellfish. When ingested these enzymes split thiamin
(Vitamin B1), an important compound in energy metabolism, and render it
inactive.
• Tannins: water-soluble polyphenols that are present in many plant foods.
They have been reported to be responsible for decreases in feed intake,
growth rate, feed efficiency, net metabolizable energy, and protein
digestibility