Submitted to: Meeting Abstract
Publication Type: Abstract Only
Publication Acceptance Date: 1/28/2014
Publication Date: 2/4/2014
Citation: Tunick, M.H., Paul, M., Van Hekken, D.L. 2014. Case Study: Variation in fatty acid profiles in milk from adjacent organic and conventional dairy farms over a 3-year period (abstract). 2014 Northeast Pasture Consortium Annual Conference & Meeting. Final Program & Abstracts p.1.
Technical Abstract: Measuring the seasonal variability of fatty acids (FAs) in milk improves our understanding of the nutritional and health values of milk. In collaboration with the Rodale Institute, Kutztown, PA, a 3-year study evaluated the seasonal variation of FA profiles of milk obtained from two farms adjacent to the Rodale experimental farm: one farm transitioned to organic in the first year (cows consumed a minimum 30% dietary energy from pasture during the grazing season) while the other was a confined conventional farm (no access to pasture). This study provided a unique opportunity to compare milk from farms of similar soil types, climate, and weather. Over the 3-year period (including 3 grazing seasons), weekly milk samples were collected and FA profiles generated focusing on the different forms of the FAs containing 18 carbons and multiple double bonds known as polyunsaturated FAs (PUFA), which have been shown to impact human health. Fatty acid analysis showed considerable variation within and between the herds from week to week and year to year. Although many factors influence the FA levels, certain trends were seen. As expected, the grass-fed animals had more variation in the PUFA levels than the conventional herd, which consumed a more uniform diet. In the grass-fed herd, the overall averages for PUFA in the 2nd and 3rd grazing seasons were consistent, with conjugated linoleic acid (CLA) and C18:3 levels 38% and 29% higher than in the conventional herd, respectively. During the first grazing season, while the herd was in transition, the differences in PUFA between the two herds were lower. The C18:2 averages were consistently lower in milk from grass-fed than the confined herd. Higher CLA levels and a low C18:2 to C:18:3 ratio are considered beneficial to human health. Findings from our research will help establish the seasonal variation in FA profiles from grass-fed animals and develop guidance to help dairy farmers produce milk with the highest possible nutritional and health values.