Foods that contain animal protein tend to be high in several nutrients that are often lacking in plant foods.
These include:
Vitamin B12: Vitamin B12 is mainly found in fish, meat, poultry and dairy products. Many people who avoid animal foods are deficient (3).
Vitamin D: Vitamin D is found in oily fish, eggs and dairy. Some plants contain it, but the type found in animal foods is better used by your body (4).
DHA: Docosahexaenoic acid (DHA) is an essential omega-3 fat found in fatty fish. It’s important for brain health and is hard to get from plant sources (5).
Heme-iron: Heme-iron is predominantly found in meat, especially red meat. It is much better absorbed in the body than non-heme iron from plant foods.
Zinc: Zinc is mainly found in animal protein sources, such as beef, pork and lamb. It is also more easily absorbed and used from animal protein sources (6).
Of course, there are also plenty of nutrients found in plants that are lacking in animal foods. Therefore, eating balanced amounts of both is the best way to get all the nutrients you need.
https://authoritynutrition.com/animal-vs-plant-protein/