Until recently, nutrition has been solely focused on the amounts of nutrients, which can be derived from ingested feed. So nearly all new feeding tables present the amounts of nutrients in feeds tuffs. They also increasingly provide estimates of nutrients apparently absorbed from a diet or even availability. Availability in this context is defined as the degree to which an ingested nutrient in a particular source is absorbed in a form that can be utilized in metabolism by the animal (De Lange and Fuller, 2000).
The excreta are not considered in the feeding tables. Nowadays in many countries or areas, farmers have to focus on ways to avoid adding nitrogen to the environment, and in addition to avoid emission of NH3. So the excreted surplus of N can become a burden to the environment Most research has focused on the amounts of nitrogen (N), which are excreted in addition to other minerals.
Was this article helpful?