From CIWF in the UK, which compiled the nutritional findings of 76 studies:
Grassfed beef has:
- Up to 50 % less fat.
- Up to 430 percent more of the healthy Omega-3 fats.
- Higher levels of anti-oxidants.
Source (summary): http://www.ciwf.org.uk/your_food/nutrition.aspx
Source (full paper): http://www.ciwf.org.uk/includes/documents/cm_docs/2012/n/nutritional_benefits_of_higher_welfare_animal_products_report_june2012.pdf
Thanks to the American Grassfed Association for bringing this to our attention.