@C_Z_ The answers to the other question you suggest all refer primarily to ALA, EPA and DHA. For those who don't know what this is (I guess this is by far the majority of people searching for Omega 3) it is very useful to have a specific question about Omega 3. If anything this question is great because it will probably be the first step to people learning about ALA, EPA and DHA.

Researching the "6-10%" claim, I can find this onegreenplanet.org article which claims that it is 10%. > "In actual fact, leather accounts for approximately 10% of the animal’s total value, making it the most valuable part, pound for pound."