Why do fish have more poly unsaturated fatty acids than cattle?

This statement is inaccurate. Cattle generally have more polyunsaturated fatty acids (PUFAs) than fish. This difference arises due to the various diets of the two groups.

Grass-fed cattle: Typically, cattle that graze on grass have higher levels of PUFAs compared to fish. Grass is abundant in omega-3 fatty acids like alpha-linolenic acid (ALA). When cattle consume this type of diet, they accumulate ALA and convert it into other PUFAs, such as eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA).

Diet of Fish: Fish, being aquatic animals, derive their PUFAs from their diet, which primarily consists of algae, zooplankton, and other fish. While some fish, like salmon, are recognized for their omega-3 content, the fatty acid composition of different fish species varies. Fish might have higher levels of specific PUFAs depending on their location, diet, and life stage.

Overall, while certain fish species may contain significant amounts of PUFAs, the general statement suggesting that fish have more polyunsaturated fatty acids than cattle is not accurate. Cattle raised on grass-based diets tend to have comparable or even higher levels of PUFAs, including omega-3s, compared to fish.