Total AA vs. Digestible AA in poultry nutrition

Dear Users,
This is an interesting forum from our Spanish community, generated by Joaquin A. Paulino from República Dominicana:

Birds do not have a crude protein requirement, they only need an amount of nitrogen for the synthesis of essential amino acids.
The ideal protein concept, investigated by Boorman (University of Nottingham) and Baker University of Illinois), is defined as the exact contribution of all amino acids with no excess or deficit for maintenance and maximum increase in body protein. In practice, it is possible to approach the ideal protein formulated with a minimum excess of essential amino acids. This reduces the use of AA as an energy source and reduces the excretion of nitrogen to the environment.

Regarding until what protein level we can descend, Rostagno et al, showed that chickens fed 0-21 days of age with 18 to 19 servings of protein were deficient in glycine + serine, for the period from 22 to 40 days, rations with 17 protein was deficient in isoleucine and valine.

The amino acids glycine and serine are very important in the excretion of uric acid in birds.
Currently there are values of digestible amino acids for poultry and pigs, there are methods that allow rapid assessment of digestible amino acids of raw materials with greater variability, we can modify the array in the program formulation in each allotment we receive. The NIR testing, and IDEA (Immobilized Digestive Enzyme assay), measures the in vitro digestibility of H. Soya in 24 hours, h. by-products and 2 hours, c. Meat and bone in 2 hours.
Joaquin A. Paulino