The presence of trans unsaturated fatty acids in ruminant meat and milk is unnatural.

It is proposed that the presence of large quantities of trans unsaturated fatty acid isomers as final metabolic products of the rumen bacteria and their consequent presence in ruminant tissues and milk is completely unnatural. This results from excessive feeding of domestic ruminants and the consequent passage of bacteria containing partially hydrogenated trans fatty acids into the small intestine. Digestion of such bacteria and the subsequent absorption of the released trans fatty acids could account for their unnatural presence in ruminant tissues and secretion in milk. It is also proposed that the feeding of ruminants, poultry and pigs with unsaturated fatty acid-containing concentrates, could also be a source of trans fatty acids which occur in their tissues.