Date of Award:

5-2026

Document Type:

Dissertation

Degree Name:

Doctor of Philosophy (PhD)

Department:

Nutrition, Dietetics, and Food Sciences

Committee Chair(s)

Stephan Van Vliet

Committee

Stephan Van Vliet

Committee

Namhyeon Park

Committee

Juan Villalba

Committee

Taylor Oberg

Committee

Marie Walsh

Abstract

How food is produced can influence both its nutritional quality and its impact on the environment. In recent years, regenerative (agroecological) farming practices have gained attention for their potential to improve soil health, biodiversity, and the nutritional value of foods. In dairy production, these practices often involve growing more diverse forage crops, reducing soil disturbance, and relying less on monoculture-grown feed rations. However, there is still limited real-world evidence showing how these practices affect the nutritional composition of milk produced on commercial dairy farms.

This dissertation explores how regenerative feeding and feed production practices influence the nutritional quality of milk, with a focus on fatty acids and bioactive compounds. The work combines a broad review of existing research with two field-based studies conducted on commercial dairy farms in the U.S. North Central region. Together, these studies examine differences in feeding strategies, forage diversity, and seasonal changes shape milk composition under real-world farming conditions.

The first research study compared milk from regenerative dairy farms employing a combination of grazing and indoor feeding to milk from a conventional dairy farm that relied on a total mixed ration richer in grains and corn silage. Milk from farms using diversified, grass-based feeding systems contained higher levels of beneficial omega-3 fatty acids and a wider range of bioactive compounds considered to have antioxidant effects. These differences reflected the types of feeds consumed by the cows, with regenerative systems relying more heavily on forages and less on grains. Farms with greater plant diversity in their feeding systems also showed signs of improved soil health, suggesting a connection between soil management, animal diets, and milk quality.

The second research study focused on seasonal changes in feed and milk composition across agroecological dairy farms in Wisconsin. Although milk composition varied across seasons, farms that implemented agroecological feed production practices were better able to maintain favorable fatty acid profiles throughout the year. Forage-and silage-based feeds consistently supported higher levels of beneficial fatty acids in milk compared with more conventional feed rations. In addition, a wide range of plant-derived compounds found in feeds were detected in milk as transformed metabolites, highlighting how cow digestion links farm practices to the final food product.

Overall, this research shows that regenerative dairy practices can improve the nutritional quality of milk while operating within real-world commercial systems. While seasonal variation remains, an important factor influencing milk composition, diversified forage-based feeding and soil-focused management practices help support more nutritionally balanced milk across the year. These findings provide practical insight for farmers, inform conversations around sustainable food systems, and contribute to a broader understanding of how agricultural practices shape the foods people consume.

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