There are many ways in which animals obtain their nutrients. Many of these animals choose to eat or absorb their nutrients.
animals all animals (meats) have protein, some plants have protein too, like peanuts.
The common protein found in all animals is collagen.
Meat and milk and protein
comparing the weight gained in lab animals consuming a test protein with the weight in lab animals consuming a standardized (reference) protein
Animals source their protein from various sources in their diets, including plants, other animals, and sometimes from insects or microorganisms.
No
Except for the protein that is used by the animal, protein can be lost in several ways. For example, if the animal has a problem with digestion or absorption, protein can be lost via the faeces. Protein can also be lost into the abdomen, and animals with kidney malfunction can lose protein via urine (eg. a protein losing nephropathy).
Collagen
It's necessary.
All animals need protein because their bodies use the protein to produce energy. Without protein, animals would not be able to create the cellular reactions that sustain life.
animals dont have protein
Yes, all animals carry protein in their bodies.