InraPorc: Where Do We Come From and Where Do We Want to Go? - Nutritional Modelling for Pigs and Poultry - page 30

the amino acid supply would not be limiting
for protein deposition. However, if one (or
more) of these values were lower than the pro-
tein deposition determined by the Gompertz
function or by the energy supply, the amino
acid supply will be a limiting factor for pro-
tein deposition. This approach also allows us
to determine the order of limitation for the
different amino acids (Fig. 2.2) .
Amino acids that are not used for actual
protein deposition will be deaminated and
there are different reasons for this deamin-
ation. If the amino acid itself is the first-lim-
iting factor for protein deposition, there will
be a minimum oxidation due to the fact the
amino acid is used with a maximum effi-
ciency lower than 100% (i.e. the minimum
oxidation is the complement of the max-
imum efficiency). If the supply of the amino
acid exceeds the protein deposition poten-
tial of the animal, the excess supply of amino

acids will be deaminated, in addition to
the minimum oxidation. A third situation
occurs when the supply of an amino acid is
the determining factor for protein deposition.
Part of the supply of the other amino acids
will then be deaminated because the supply
of one amino acid is limiting and it is the im-
balance in amino acid supply that provokes
the deamination. Increasing the supply of
the limiting amino acid would improve the
balance and improve the efficiency of the
utilization of the non-limiting amino acids.
The way amino acids are used can be shown
in a dynamic way in InraPorc ( Fig. 2.3) .

Modelling Amino Acid Utilization
vs an Ideal Amino Acid Profile

The approach of separating basal endogen-
ous losses, maintenance requirements and

Fig. 2.2. Screenshot of InraPorc illustrating the order in which different factors can be limiting for protein
deposition. From 30 to 70 kg of body weight, energy intake is limiting protein deposition. After 70 kg of
body weight, protein deposition is determined by PDmax. In this simulation, the supply of amino acids does
not limit protein deposition.