What is a nutrient?

A nutrient is defined as a feed constituent that aids in the support of life. Nutrients play essential roles in various bodily functions, including providing energy, facilitating growth, maintaining health, and supporting metabolic processes. In the context of horse nutrition, nutrients include carbohydrates, proteins, fats, vitamins, and minerals, all of which are crucial for the overall well-being of the animal.

The other options do not accurately describe what a nutrient is. Harmful substances in feeds, for instance, could contribute to health issues rather than support life. Similarly, a specific type of grain for horses does not encompass the broader definition of nutrients, as not all grains contain the complete set of essential nutrients. Lastly, a substance that causes disease contradicts the fundamental role of nutrients, which is to promote health and support biological functions.