So obviously I got the analysis I wanted even if the sought after ratio isn't *quite* what I hoped for. The ratio of 5.5:1 omega 6:3 is not superb, but it is significantly closer to the "grass-fed" meat than most pork. The literature I've read for pork generally shows 6:3 ratios ranging from 10:1 to 20:1. In the paleo-sphere there is a loose "cut-off" for meat to be considered healthy at 4:1. Both corn and soy weight things heavily toward linoleic fatty acid (n6) vs alpha-linoleic fatty acid (n3). Pigs are quite adept at storing any fats they consume, so it doesn't surprise me that a grain fattened pig would have a ratio skewed toward 6.
I am pretty sure the absolute dose of omega 6 is lower per unit of fat from my pork than from "conventional" pork. I'm not sure whether the omega 3 is any higher, or if it is just that a lower 6 pushes the ratio toward a more favorable level.
I'd have liked it if the ratio was something like 2:1, but I'm not too disappointed in this finding. I should really test again with a pig that's been on pasture/whey for a few months (as opposed to hay/whey). There are just so many variables to account for, and my testing budget is way too limited to attempt to address all of them.
As with any lead worth following a result like this just provides me with more questions -
1. How would the results vary with a sample of leaf lard instead of backfat? The leaf lard we rendered recently seems significantly more saturated than the backfat. Would it have different levels of essential fats too?
2. Would the results vary from a pig on fresh growing green pasture? The submitted sample came from a pig on haylage all winter. It had not eaten anything really green in months. Brassicas are supposedly rich in omega 3s. How would the results vary if the pigs got a bunch of brassicas to munch on for two months prior to slaughter?
3. Where did the omega 6 fats come from? Two prominent possibilities - The whey has very little butterfat in it. Some loads have virtually none, others have a thin skim of it. But perhaps all it takes is a little bit. The grains I fed the pigs could have contributed even though I fed paltry amounts. We sent the largest few pigs to slaughter. If the one that provided the sample got more than its share of the grain ration each time I fed it that could be the source of "elevated" omega 6. A third (longshot) would be the internal milieu of the individual pig. I've read that there is a bit of variation within a given cohort of animals even if they're all eating the same feed. I read one study where the authors proposed selecting for pigs adept at stockpiling omega 3s, meaning they would "naturally" have a more favorable ratio than their peers. An even longer shot is the tiny amount of stale bread I fed them. Each pig got about one loaf per week, and the bag on the bread claims it is "fat-free", so I doubt it is much of a source of omega 6s.
4. Why did the lab not detect any docosahexaenoic acid (DHA)? Pigs and humans are inefficient at converting alpha-linoleic acid into DHA, but they can both do so. I'd expect there to be at least a trace of it. Should I try a different lab if/when I test the fat again?
So... all in all I'm not dissatisfied. I only have one pound of ground beef left and then I'll have only pork for meat for the next month or so. If the much vaunted ratio had come back 20:1 I'd have thought twice before proceeding to eat tons of the stuff. As it is I'm not too worried. I don't overdose myself with other sources of omega 6s like fried food from fast-food franchises nor do I cook in corn oil at home.
I do think it is interesting that our pig's fat balance appears to differ significantly from conventional lard. It has a lot more monounsaturated fat than "normal" lard, much less polyunsaturated, and a lot less saturated fat. I joke about refining some pig oil for my salad this summer, but with the amount of oleic oil (essentially olive oil) in there it would probably yield a good amount... I don't put much stock in the conventional wisdom that saturated fats are unhealthy. But if I did, the monounsaturated:saturated levels would be a compelling reason to eat my pork instead of other pork.