Background and methodology:
The author extensively reviewed results from various studies regarding nutritional differences between pasture-raised and conventionally raised animals (beef, dairy, poultry, swine and lamb).
Findings:
Fat from pasture-raised animals tend to have a greater proportion of healthy fats (conjugated linolenic acids or CLA, and omega-3 fatty acids) and higher level of vitamin E. Milk from pasture-raised cows generally contains higher levels of CLA and has different proportions of other fats. However, pasture-raised cows might have lower milk yields. Extrapolating from these findings to support nutritional benefit claims is not straightforward. Even if the fat from pasture-raised beef has a healthier profile of fatty acids, the amount of fat is far less, i.e., consumers will not get a substantial amount of those fatty acids. Vitamin E levels are higher but still too low to make much difference in requirements. The author concluded that pasture-raised animals most likely have a better nutritional status, but whether consumers benefit depends on the season, the animals’ length of time on pasture, species and nutrients being compared.
Reference:
Auld, G. (2004). Is better nutrition a justification for choosing pasture raised animal?Paper presented at the Animals in the Food System Conference, Kellogg Biological Station, Hickory Corners, Michigan, Nov. 2 - 4. Available on-line at: http://mottgroup.msu.edu/portals/0/animals_in_food_files/AITFS-Auld.pdf