Just as for the other species, genetic progress has a considerable influence on dietary amino acid concentrations. Over the last 30 years, production to a constant age has increased by more than 40 percent, while feed consumption has been reduced by about 10 percent.
An important consequence of this genetic progress has been a change in the daily amino acid requirements. It has also called into question the practice of phase feeding, since productivity remains high over longer and longer periods.
The best units nowadays have daily egg outputs of over 60g/bird right up to 52 weeks of age.
Classically, daily requirements have been expressed in mg / day. While this type of expression may be very easy for the formulator to use, it does not allow for genetic progress, nor for genotypic differences.
Those genotypes, which produce large eggs, have larger daily requirements than those, which produce small eggs.
Most Researchers agreed to express requirements in mg of amino acids per gramme of eggs produced. This method enables us to tackle the Â« requirement Â» starting from numerous experimental data sources. It is more precise.
The synthesis carried out according to this method shows it to be an excellent way of determining requirements.
The concept of ideal proteins is a means of expressing the requirements for amino acids as a percentage of the requirement for LYS. There is a limited interest in applying this concept to layers.
It implies that a balance between the different amino acids is necessary for optimizing requirements. That would suggest that high protein or amino acid levels would have a negative effect on performance.
In fact, the formulator should make a point of satisfying the requirement for the following amino acids: MET - CYS - LYS - THR - TRP - ISO and VAL. This is only valid for diets and raw materials in common usage.
Bird requirements and formulation of diets should be made in terms of digestible amino acids. By formulating in digestible Amino Acids the requirements of the birds are more easily satisfied., to reduce the necessary safety margins and assess the raw materials according to their true biological value.
Formulation according to total amino acids leads to the same nutritional value being given to all raw materials irrespective of their digestibility. That leads naturally to increasing the safety margins in order to guarantee fully meeting the requirements of the birds.
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Article made possible through the contribution of Hendrix Genetics