Concept:The animal by-product illustrated in the diagram is bone meal, which is commonly used as a mineral supplement for farm animals.
Explanation:Bone meal is prepared by crushing and processing animal bones.
It is very rich in calcium and phosphorus, both of which are needed for healthy bones and growth.
Farmers add bone meal to animal feed to supply these essential minerals.
Among the given options, calcium is the mineral supplied in large amounts by bone meal.
Sodium, iron, and nitrogen are not the main nutrients provided by this by-product.
Therefore, the animal by-product is fed mainly as a source of calcium.
Answer:Calcium.
