Location: Dairy and Functional Foods
Title: Case history: tracking the nutritional value of milk from a transitioning-to-organic dairy herd Authors
Submitted to: Meeting Abstract
Publication Type: Abstract Only
Publication Acceptance Date: January 30, 2013
Publication Date: February 7, 2013
Citation: Van Hekken, D.L., Tunick, M.H., Paul, M., Ingham, E.R., Seidel, R., Tomasula, P.M. 2013. Case history: tracking the nutritional value of milk from a transitioning-to-organic dairy herd (abstract). Northeast Pasture Consortium Final Program and Abstracts 1:20. Technical Abstract: Research is focusing on many of the factors that influence the amounts of biologically active compounds (BACs) in milk, such as the influence of on-farm and seasonal factors, to improve the nutritional and health values of milk. In collaboration with the Rodale Institute, Kutztown, PA, our current study is evaluating the composition of milk obtained from two farms adjacent to the Rodale experimental farm: one farm was transitioning to organic (cows eat a minimum 30% dietary energy from pasture in grazing season) while the other was a confined conventional farm (cows had no access to pasture). This study provides a unique opportunity to compare milk from farms of similar soil types, climate, and weather. Over a 75-week period (including 2 grazing seasons), weekly milk samples were collected and assayed for composition and profiled for fatty acids (FAs), proteins and peptides, and volatile flavor compounds. The overall fat, lactose, protein, and total solids contents of the milk samples were similar from both farms throughout the study although the fat levels were slightly higher for the transitioning herd during the first grazing season. Fatty acid analysis showed that the conjugated linoleic acid (CLA) content in milk was higher and the ratio of polyunsaturated-to-monounsaturated FAs was lower from the transitioning herd than that for the conventional herd. Protein and peptide profiles were typical of fresh milk and showed minimal protein breakdown. A few of the minor volatile compounds, which are associated with fatty, fruity, or pine aroma or sweet taste, were found only in the herd on pasture. Ongoing research includes analysis of the mineral and vitamin distributions in milk, the antioxidative and hypertensive properties of the milk proteins, and the digestibility of raw and pasteurized milk from both feeding regimens. We will correlate these results with the Rodale pasture data to determine transitioning, seasonal, and pasture quality (summer drought) effects on composition and BACs levels. Findings from our research will help establish factors that impact the nutritional and health values of milk from grass-fed animals and develop guidance to help dairy farmers produce milk with the highest possible nutritional and health values.