Amino acids which are said to be indispensable cannot be synthetized by the organism. They must therefore be provided by feed so that they can be used in the synthesis of body proteins and thus support the process of growth. Thus, when the supply with one of those indispensable amino acids does not meet the animal's requirement for this amino acid, it is said to be limiting.
Studies on the requirements of amino acids for growth have made it possible to show that the composition or the profile of body proteins in essential amino acids is relatively stable. This profile varies only slightly depending on the species under consideration and also depending on the requirements of the other major physiological functions of the organism, such as digestion, maintenance and activation of the immune system. At the same time, studies of the use of the main limiting amino acids have made it possible to estimate the efficiencies of use for each amino acid for body protein deposition. Thus, for a species and / or a given physiological stage, it is possible to determine the dietary profile in amino acid which satisfies all of the animal’s requirements and thus optimizes its growth. The concept of an optimal profile in essential amino acids in feeds is commonly called ideal protein.
In practice, as lysine is the first limiting essential amino acid for growth, the requirement in each essential amino acid is expressed in relation to this amino acid. The ideal protein is thus represented by a profile in which the supply of each essential amino acid is expressed as a percentage of the dietary lysine content. Each of these ratios can thus be directly introduced as a constraint in feed formulation.
Amino acids which are said to be indispensable cannot be synthetized by the organism. They must therefore be provided by feed so that they can be used in the synthesis of body proteins and thus support the process of growth. Thus, when the supply with one of those indispensable amino acids do not meet the animal requirement for this amino acid, it is said to be limiting.

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The ideal protein profiles

Existing studies and the numerous profiles of ideal protein which have already been published now enable this concept to be broken down for each species. Moreover, increased knowledge concerning the use of amino acids and their factors of variation make it possible – when useful - to break down the concept for each physiological stage within a species.

Using literature reviews and experimental collaboration, AJINOMOTO EUROLYSINE S.A.S. as proposed ideal protein profiles which provide information about the main potentially limiting amino acids in commercial feeds for pig and poultry. These profiles have been published in AJINOMOTO EUROLYSINE’s different technical bulletins and the following table summarizes them. Ratios for each amino acid are expressed in relation to lysine on a standardized ileal digestible basis.

Practical interest of the ideal protein

The application of the concept of the ideal protein in feed formulation thus makes it possible to adjust the supply of indispensable amino acids to the requirements of animals in order to avoid deficiencies and also to limit excesses. These excesses, which are mainly caused by protein-rich raw materials, such as soybean meal, provide certain amino acids which go beyond the animal’s requirements; moreover, they have to be catabolized by animals and they are at the origin of the excretion of nitrogen compounds which are transformed into nitrates in the environment. In the implementation of the concept of the ideal protein, feed-use amino acids are indispensable ingredients to optimize the balance of amino acids in feed formulas – meeting objectives of performance, profitability and respect for the environment.

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