http://orgprints.org/7320/ Milk fatty acids in relation to feeding practices on Dutch organic farms de Wit, Jan Wagenaar, Jan Paul de Vries, Anneke Baars, Ton Food security, food quality and human health Dairy cattle Various recent studies have indicated positive interactions between organic animal production and poly-unsaturated fatty acids, particularly CLA and omega-3. In this paper, we present the monitoring results of 15 organic farms concerning the rela-tionship between feeding practices and fatty acid pattern. The results indicate a strong negative effect of maize and grass silage and concentrate feeding on CLA levels in milk fat. On the other hand, feeding fresh grass has a positive effect. Omega-3 levels in milk fat seem less related to feed characteristics: similar relations to those with CLA seem to exist, but feed composition explains the variation in omega-3 levels only to a limited extent, while there is a large farm influence. This might be related to the energy balance of the cows. A comparison of measured CLA and omega-3 levels in organic milk with common levels in conventional milk shows a small difference during the stable period. Effects of adding oil - as a possibility to improve the level of CLA and omega-3 in a way that is organically acceptable - are explored, but effects remain small. 2006 Conference paper, poster, etc. NonPeerReviewed application/pdf http://orgprints.org/7320/1/jan_de_witodense_papermilkdef.pdf application/pdf http://orgprints.org/7320/2/7320_Wit.pdf de Wit, Jan; Wagenaar, Jan Paul; de Vries, Anneke and Baars, Ton (2006) Milk fatty acids in relation to feeding practices on Dutch organic farms. Joint Organic Congress, Odense, Denmark, May 30-31, 2006. http://orgprints.org/7320/http://orgprints.org/7320/1/http://orgprints.org/7320/2/