Ideal protein concept:
Balance is essential


In growing animals, the ideal protein is a concept where the amino acids pattern (defined as a percentage of lysine) maximizes growth, nitrogen retention or another response criterion. In this profile, all indispensable amino acids are equally limiting for performance, just covering the requirements for all physiological functions. Lysine has traditionally been used as a reference because it is the first limiting amino acid for growth in pigs. Although the concept of ideal protein was developed in the late 1950s and early 1960s, one of the first reference studies in pigs was published only in 1989. It is frequently assumed that the ideal protein profile does not change for a given growing stage. In practical nutrition, this offers the advantage that the lysine requirement will vary (per kg of feed or per MJ of energy), but not the ideal amino acids profile expressed relative to lysine. Each of these ratios can thus be directly introduced as a constraint in feed formulation.

Existing studies and the already published ideal protein profiles now enable this concept to be applied for each species. Moreover, increased knowledge about 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 collaborations, AJINOMOTO EUROLYSINE S.A.S. proposes ideal protein profiles. These profiles have been published in AJINOMOTO EUROLYSINE S.A.S.'s technical bulletins (Tables 3, 4 and 5). The ratios for each amino acid are expressed relative to lysine on the digestible basis (SID for swine and true digestibility (TD) for poultry.

Piglet Grower Finisher
Lysine100100100
Methonine + Cystine606060
Threonine656768
Tryptophan222019
Valine70> 65> 65
Isoleucine535353
Leucine100100100
Histidine323232
Phenylalanine + Tyrosine959595
Arginine424242

Table 3. Ideal amino acids profile for growing pigs feeds (in % of lysine SID)

Lactating sow
Lysine100
Methonine + Cystine60
Threonine> 70
Tryptophan24
Valine85
Isoleucine55
Arginine42

Table 4. Ideal amino acids profile for sows feeds (in % of lysine SID)

Broiler chicken and turkey* Layer
Lysine100100
Methonine + Cystine7585
Threonine**6770
Valine8090
Isoleucine6780
Arginine105110
Tryptophan1724
Histidine36
Leucine105
Phenylalanine + Tyrosine105

* Values for turkey come from those for broiler chicken; some variations are possible.

** Due to the specific properties of threonine, its requirement increases with the body weight of the animal and increases in case of bad health conditions (gut disease, dirty environment,…)

Table 5. Ideal amino acids profile for poultry feeds (in % of lysine TD)

Practical interest of the ideal protein

The application of the concept of the ideal protein in feed formulation makes it possible to adjust the supply of the indispensable amino acids to the requirements of animals in order to avoid deficiencies and limit excesses. These excesses, which are mainly caused by protein-rich raw materials, such as soybean meal, provide some amino acids which go beyond the animal's requirements; they have therefore to be catabolised 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.

For further information, please read our technical bulletins: numerous experimental results are reported.

 

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