If you used cold pressed in Germany you can buy online from Zooplus and it is very well priced. I am not absolutely convinced of the science recommending it over any other commercial product but you can mix with raw and mine do well on it as part of a wide diet. The book K9 Kitchen by Monica Segal makes authoritative reading as she started her personal research from owning a dog with extreme allergy/intolerance issues. She dismisses the bandwagons and myths but her recommendations are quite technical but are based on thorough science. I am starting research on nutrigenomics, hadn't heard of it, which is microbiology and trying to understand the role of our gut bacteria. Overwhelmingly these scientists are finding that good bacteria are being reduced by over processed food, antibiotic overuse, including in rearing of meat animals and that prebiotics can encourage the good guys in humans. Dogs are of course less omnivore but kefir or other fermented milk in size appropriate dose may help reduce reaction and increase uptake of nutrients and should not have lactose intolerance problems. I have IBS hence my interest.
I agree with Dottie about keeping it simple, really simple as unless you see the ingredients you can't be absolutely sure. The gluten free products mean not produced in the same factory ! I can buy grass reared ox heart etc but know that many folk can't, and cook or not cook is not terribly important. Forthglade wet feeds are produced in Devon and probably( I can check) take from the abbatoirs in Southwest which would mean better reared meat. I wonder where Wainwright etc source theirs. Grain fed stock kept indoors have lower Omega 3 levels than outdoor grass reared and O3 helps reduce inflammation.