A cow's herbivorous diet indicates that it is a (n

The answer is a primary consumer.

In the food chain, plants are considered producers because they produce their own food. Animals consume plants, so animals are consumers. They can be primary, secondary, or tertiary consumers. If animals eat plants (producers), they are primary consumers. If animals eat primary consumers, they are secondary consumers, etc. A cow's herbivorous diet indicates that it eats plants, so the cow is a primary consumer.