What is the difference between an animal unit (AU) and an animal equivalent unit (AEU)?

The distinction between an animal unit (AU) and an animal equivalent unit (AEU) lies primarily in their definitions and measurements. An animal unit is typically defined based on a standard measurement of live weight, often using a benchmark like a 1,000-pound cow. This standardization allows for consistent calculations across different livestock species when assessing overall nutrient management impacts.

In contrast, the animal equivalent unit is designed to categorize different types of animals based on their nutrient excretion rather than their live weight alone. The AEU takes into account the animal's annualized weight, which can vary based on factors like age, diet, and sex, and provides a more nuanced approach to understanding their environmental impact, particularly in terms of nutrient management.

This understanding is crucial in nutrient management planning, as it helps in assessing appropriate livestock densities and their effects on land and water resources. Hence, the distinction made regarding live weight versus annualized weight gives clarity to how these units are applied in practices surrounding nutrient management.