New Zealand Study: Diverse Pastures Change Milk, Meat and Human Blood Chemistry

New Zealand researchers have found that grazing sheep, cattle and deer on a mix of pasture plants, rather than one grass species, changes the biochemical make-up of the milk, beef, lamb and venison produced. In new human feeding trials, the researchers also found changes in the blood of people who ate the meat.

The approach, called "functional diversity," mixes several forage species in the same paddock — grasses, herbs such as plantain and chicory, and legumes such as alfalfa and clover. This replaces the grass monocultures common in conventional farming. In lab trials, researchers compared conventional, multispecies and functional-diversity grazing in sheep, cattle and deer, recording improved growth, feed efficiency, milk production and animal well-being. The functional-diversity systems also cut nitrogen loss to the environment by about 30% in sheep and 42% in dairy cows.

Using metabolomics — a technique measuring thousands of small molecules called metabolites, made in the body — the team analysed milk, beef, lamb and venison from each system. Milk from cows on functional-diversity pastures had higher levels of compounds that help the body burn fat for energy and support red blood cells and mood-related brain chemicals. It also had half the level of a compound linked to a higher risk of heart disease and dementia.

Venison from deer on functional-diversity pastures showed the largest shifts — a 27-fold increase in antioxidant and anti-inflammatory compounds, and a 59-fold rise in metabolites that regulate oxidative stress. Lamb and beef from the same systems showed increased compounds linked to antioxidant activity, cardiovascular and mental health, anticarcinogenic activity and better nutrient absorption.

To test effects in people, the researchers ran what they describe as the first-ever randomized feeding trials. Each participant ate beef or lamb from conventional, multispecies and functional-diversity systems, with blood tested each time. Beef from functional-diversity systems raised metabolites linked to cholesterol metabolism, vascular function and reduced colon-cancer risk. Lamb raised metabolites linked to neuroprotection, cardiovascular health and reduced inflammation. The study, led by Anita Fleming, appeared in the Journal of Animal Science in 2025 (DOI: 10.1093/jas/skaf254).