Animals obtain their nitrogen primarily from plants. Plants absorb nitrogen from the soil and incorporate it into their tissues. When animals consume plants, they obtain nitrogen from the plant proteins. Additionally, some animals obtain nitrogen indirectly by consuming other animals that have already obtained it from plants. Nitrogen in the soil can also be transformed into nitrites and nitrates by bacteria through the process of nitrogen fixation. However, animals primarily obtain their nitrogen from plants rather than directly from nitrites, nitrates, or bacteria.
