Progress of amino acid nutrition for diet protein reduction in poultry

M. T. Kidd, I congratulate the team of researchers for the information contained in the article on the reduction of crude protein (CP) in poultry feed. Although the matter was well founded, I would like to make a consideration. In addition to what was discussed, which highlighted the complexity involved in reducing CP in poultry diets, including the need to include some amino acids considered non-essential in the feed depending on the level of reduction, as reported, I believe that some other aspects should be considered. As these amino acid supplementation is effected on the basis of information on the relationships of essential amino acids to lysine contained in the ideal protein of different animal categories, it would also be important to consider the dynamic character of the ideal protein. This is because these relationships can be altered, for example, by the immune challenge of birds and also by the thermal environment, as well as by the interaction between these factors. As the decision to reduce the CP of the rations must be made, if all these aspects are considered, I think that this practice still lacks some important information to be carried out in order to sustain the performance of the birds.