Steve's Domesticated Prey Hypothesis
Domesticated prey animals, even if they are fed the same food, will not have the same types of fat as wild prey animals because they don’t need the same type of fats.
A wild animal needs to hear and see well, think and move quickly in order to survive; it needs significant amounts of DHA, a very fluid fat, to do these tasks well. Generally speaking, areas of the body that require rapid movement contain DHA. I suspect that wild prey animals will convert more of the ALA they consume (from grasses) to DHA than those animals, like domesticated animals, that have no need for rapid movement or alertness.
It’s expensive – in terms of energy and nutrients – for an animal to convert ALA to DHA and then store the DHA. The domesticated pasture fed animal has no need to convert the ALA it eats to DHA, so it probably won't make as much DHA as the wild animal. Why waste the energy converting ALA to DHA when it’s not needed? DHA requires greater protection against oxidation than ALA, putting a further strain on the animal. When it comes to storing fat, saturated fats are much more stable.
A pasture-raised ruminant, with little need to think and move quickly, would probably store as much fat as possible as stable, saturated fats, and use much of the polyunsaturated fats it consumes for what little energy needs it has. The wild animal, with a greater need for the polyunsaturated fats, probably converts more of the saturated fats to energy.
Fed the same foods (different quantities based upon activity levels), domesticated prey animals would therefore have more saturated fats, and a higher percentage of their polyunsaturated fats will be 18-carbon fats than with wild prey animals, who would have a higher percentage of long-chain polyunsaturated fats, particularly DHA.
