Tryptophan requirement of 22 to 34-week-old caged-laying hens

Dr Mike Persia, I congratulate the research team for the fact that the requirement for the amino acid under study, in this case tryptophan, was established in grams per day. One detail that I think is important is that, as the requirements for essential amino acids are dependent on the level of digestible lysine (LD), it would be important, even if in the summary, to include this information. A second consideration, which is still related to the first, refers to the fact that the use of an inadequately low ratio, of some other essential amino acid with LD, the determined requirement of the amino acid under study, in which case the tryptophan would be compromised , resulting in an underestimated tryptophan: LD ratio. This is due to the fact that the use of a certain essential amino acid with a low relation to LD, results in an unexpected increase in the need for LD. This increase in LD, therefore, results in underestimating the ratio of the amino acid under study. These are the reasons why the requirement for a particular amino acid should be established in grams per day. This statement I make because of work that our team of researchers conducted to determine the ideal relationship between sulfur amino acids (Aas) and LD in laying hens diets. In these works it was consistently found that the best relationship between two amino acids corresponded to 1.00Aas: 1.00 LD, not 0.90Aas: 1.00 LD as established in nutritional requirement tables for poultry and swine. So when I use the 0.90Aas: 1.00LD ratio, all other ratios of essential amino acids to LD are underestimated, since the demand for LD increases to meet the real requirements of the animals. However, even with this inadequate relationship if the result is expressed in grams per day, there is no underestimation of the requirement.