Grass-Fed Angus From Southern Chile: What One Study Shows

When people talk about grass-fed Angus, they usually picture the American Midwest or the Southern Plains. Researchers in Chilean Patagonia have studied what happens when Angus-cross cattle finish on cold, windswept pasture at the bottom of South America. Their work is a useful case study, not because Chilean beef is better or worse, but because it shows how many levers sit between "grass-fed" and the nutrition of the finished steak.

The study in brief

The research was carried out at INIA Kampenaike near Punta Arenas, in Chilean Patagonia, and published in an open-access journal. The team worked with 40 Angus-cross steers raised on pasture, weaned at six to seven months and slaughtered at 18 to 20 months at about 448 kilograms live weight. For comparison they used 10 calves from the same maternal herd, weaned at seven months and given 2.5 kilograms of corn plus 1 kilogram of commercial concentrate daily on winter pasture for 47 days before slaughter at about 316 kilograms.

The groups were unequal in size, which the authors acknowledge through their statistical approach, and the animals came from a single research station. That limits how far you can generalize. It does not limit how much you can learn about the mechanisms.

What the researchers measured

They sampled the longissimus muscle, the ribeye, and looked at fatty acid composition, intramuscular fat and tenderness. A few numbers stand out:

• Saturated fat made up 45.8 percent of fatty acids in the pasture steers and 43.9 percent in the calves.
• Monounsaturated fat was higher in the steers (39.1 percent versus 34.3 percent), while polyunsaturated fat was higher in the calves (11.9 percent versus 7.65 percent).
• Intramuscular fat averaged 2.0 percent in steers and 1.1 percent in calves. Both are lean by the standards of U.S. marbling grades.
• Both groups had a low omega-6 to omega-3 ratio, 1.75 for steers and 1.96 for calves.

The omega-3 twist

Here is the part that surprises people. As a percentage of fatty acids, total omega-3 was higher in the calves (4.00 percent versus 2.80 percent). As milligrams per 100 grams of fresh meat, the steers were higher (32.8 versus 22.8). The older steers simply carried more intramuscular fat, so a smaller share of a larger pool still added up to more on the plate.

That is a good lesson in how to read any nutrition claim. Always ask what the unit is. If you are interested in the broader question, our article on finishing and marbling covers why age at harvest and energy intake change fat deposition.

Tenderness and eating quality

Shear force values were low in both groups, which generally indicates tender meat, with the calves slightly lower than the steers. The authors describe the calf meat as more tender. The units reported in the paper are a little inconsistent between the table and the methods section, so treat the comparison as directional. The practical point is that young cattle on good forage, whether or not they get a short grain boost, can produce meat that shears easily.

Why geography matters

Patagonia has cold winters, strong wind, short growing seasons and cool-season forages. Cattle there may spend part of the year on dormant or stockpiled pasture, which is why the calf group in this study got supplemental feed on winter pasture. Compare that with a humid Southeastern U.S. operation grazing warm-season grasses, or a Nebraska operation grazing native range. Plant species, maturity and season change the fatty acids, antioxidants and energy density in the forage, and those flow through to the animal.

A Michigan State paper comparing a mixed-species pasture to a grain ration found the pasture had higher antioxidant compounds and a far lower omega-6 to omega-3 ratio, and that the pasture's profile changed across months and years. If forage changes that much within one site, it will change more between hemispheres. Any statement like "grass-fed Angus is X" should come with the system, the place and the season attached.

What the case study does not tell us

It does not tell us that Chilean grass-fed beef is nutritionally superior to American beef, or the reverse. It does not compare Angus with other breeds. It does not test consumer health outcomes. It reports composition in a single muscle from animals at one station. Responsible interpretation stops there.

Lessons for producers

• Describe your system, not just your label: forage types, days on pasture, any supplement, age at harvest.
• Match your claims to the unit. Percent of fat and milligrams per portion can point in opposite directions.
• Expect your numbers to differ from published ones, and test your own beef if composition is central to your brand.

Feeding and grazing plans are the controllable part. farm.fm's page on pasture management for Angus herds is a practical place to start thinking about forage quality.

Lessons for buyers

Ask where the cattle were raised, how they were finished and how old they were. A steak from a young, forage-fed animal can be tender and flavorful, while one from an older grass-finished animal may carry more fat and eat differently. Neither is automatically "healthier." Match the beef to how you plan to cook it, and consult the USDA beef grading information if you want to understand how marbling is classified.

For deeper reading, the Chilean study is available through the National Library of Medicine's PubMed Central archive. You can also look up regional suppliers through the Agriculture Directory. This site is independent and is not affiliated with the American Angus Association or Certified Angus Beef, and figures from a single trial should not be treated as industry averages.

In the end, geography and system matter more than a single word on a package. The Patagonian trial is a reminder to ask better questions, not to settle for easy answers.