Response of broilers to digestible sulfur amino acids and threonine intake: Maximum economic return

Matheus and Team, Congratulations for this paper. A clear example of the importance of selecting the correct model to implement precise nutrition. Kudos!

Nutritionists should pay attention to both EAAs and so-called NEAAs in diets to maximize economic returns in animal production. The ratio of NEAAs to EAAs in the body of animals (eg, pigs and chickens) is 60:40. We should not ignore the more abundant group of amino acids in animal nutrition and feeding.

Congratulations to the authors for publishing such a nice research in Engormix. One remark that could be done, is that based on this design, it's not possible to define an ideal ratio of these amino acids to lysine, since lysine is in excess (as other amino acids). With enough trials with many different amino acids you might eventually get there but a different design might be more interesting. Once you have defined ideal protein ratios, economical optimization have to be decided based on responses to variation on the level of ideal protein that optimizes the economical return. I recognize that ideal protein ratios are not fixed but vary with age, breed and gender, especially. Ideally, they should be determined using mechanistic models, like the one developed by some of the authors at UNESP in Brazil. Please don't take this as a criticism. Just exploring some other aspects related to this research. This is not really a right or wrong issue.

Yes of course What is the difference between NEAAs and EAAs ?

Dear Matheus, dear authors,

Indeed, a nice study, and thank you very much, as research on SAA and Thr responses for modelling and optimization purposes became scarce in recent years.

While I agree and applaud the dose-response data and the way you utilised them, I would like to add that both SAA and Thr have a very high involvement in maintenance metabolism and as functional amino acids. Therefore, responses depend on many factors concerning production conditions, climate, hygiene and health, feed raw materials, etc. So, please keep generating data suitable for modelling purposes.

Congratulations for this interesting and excellent research. Although I would like to say that "the minimum cost approach", as mentioned in the Introduction, is not the "accepted economic parameter for maximizing income" rather microeconomic theory states that it "is the point where the Marginal Cost intersects the Marginal Income curve" (gross margin).

I think I like everything about your paper and agree with the other comments, except for the title. I think you measured responses to levels or concentrations, %'s, not intake. Sometimes people measure responses to intake, which gives high R2 values, but then another equation is needed to relate intake to concentration to know how much to put in the feed. As for how to find the ideal balance of amino acids: You could graph all the recommendations by various people / groups and include the profile in the egg. It suggests to me that many generations of evolution resulted with the hen knowing what her chicks need. Until someone proves the hen wrong, the egg is a pretty good starting point for determining what balance chicks need.