What are organic byproducts, and how are they quantified?
Organic by-products, or “wastes,” of the livestock industry include a variety of materials such as solid and liquid animal manures, used bedding, spilled feed, and a variety of other substances. Most livestock-associated organic by-products are animal manures. The amount and consistency of manures varies with animal type, climate, feed ration, animal age and health, and other factors. To compare manure production between animal types or between animals of the same type, manure production is expressed in terms of 1,000-pound animal units. For reference, a single dairy cow weighs about 1,400 pounds, or 1.4 animal units. A typical steer weighs about 1,000 pounds, or 1 animal unit, and most hogs weigh between 200 and 300 pounds, or 0.2 to 0.3 animal unit. A mature broiler, on the other hand, weighs between 4 and 5 pounds, so it takes as many as 250 birds to make up an animal unit. Manure production and characteristics have changed over time. Livestock tend to be larger and thus produce mor
