Conventional nutritional wisdom holds that salmon is automatically better for us than beef, but that judgment assumes the beef has been grain fed and the salmon krill fed; if the steer is fattened on grass and the salmon on grain, we might actually be better off eating the beef. (Grass-finished beef has a two-to-one ratio of omega-6 to -3 compared to more than ten to one in corn-fed beef.) The species of animal you eat may matter less than what the animal you’re eating has itself eaten.