Author: Herr Dr. Amoneit
Last saved by: Saritas, Sevim

(How) is Forage Intake Related to Phytanic Acid Content in Cow Milk? - A Review
Anjo Elgersma, Independent scientist, P.O. Box 323, 6700 AH Wageningen, the Netherlands
Dr. Mette K. Larsen, Aarhus University, Aarhus C., Denmark

In the Netherlands, in 2012 retailers introduced the label “Weidemelk” (“pasture milk”)  for milk and dairy products produced by cows that are kept at pasture at least four months per year and 6 hours per day, while dairy cooperatives started paying their farmers a premium for such milk (€ 0.50 / 100 kg milk). A marker for authenitifcation of pasture-based milk is desirable for fraud detection. Phytanic acid (PHY) is a branched-chain fatty acid, produced by bacteria from enzymatic degradation of chlorophyl in the rumen. PHY cannot be synthesised de novo by mammals, and thus its presence in milk and animal-derived products depends exclusively on feed, especially on green materials, i.e. grass and forage which contain chlorophyll. Since the proportion of grass in animal rations often is higher in organically raised cattle, PHY has been proposed by German researchers as a marker for for pasture-fed milk and dairy products, as well as for organic dairy products. However,  Danish findings indicated that total PHY content is not necessarily directly correlated with the intake of green feed, being linked in a more complex way to the whole diet. Recently, a Dutch study showed that PHY content was not a suitable indicator of milk produced by pasture grazing or organic/biodynamic farming systems. The aim of this review is to compare various studies, further explore the effect of fresh grass in cows’ diet and of organic/biodynamic farming systems on PHY and its isomers (SRR and RRR) in milk, and discuss implications for the verification of farm management system.