Optimal tryptophan: lysine Ratio for 25-40 Kg Growing Pigs Fed Diets Containing 35 % Distillers Dried Grains with Solubles

The immunotolerant action through the microbiome is also interesting as it allows Lactobacillus Alistipes to use tryptophan as an energy source. The product of this degradation is indoleamine 2-3 dioxygenase 1 which in turn activates the Ahr receptor (Aryl Hydrocarbon Receptor) whose activation allows the production of IL 22, IL 10.

DR John Htoo, I think I was not clear enough in my considerations. My considerations were exactly highlighting the merit of the work for having used a suboptimal level of lysine. The suggestion that I made of using a reference treatment with lysine level in the animal's requirement, would be just to prove that the level of lysine in the test diets would be below the animal's requirement. I understand perfectly the correctness of maintaining the relationships of the other essential amino acids with the lysine just above that recommended in the ideal protein for the animal category, under study, thus guaranteeing lysine as the second limiting amino acid. I fully agree with the methodology used in this study, my intention was to highlight that detail.

Dear Hans, As your old professional partner from ID-DLO Lelystad (Wageningen University in The Netherlands) I am happy to know that you are still very active in the nutritional research on pigs. Your work I find very interesting and worthy to comment as follows: Optimizing Trp:Lys ratios in diets for grower pigs (without or with DDG) has been subjected to many studies across the world. From my perspective, in your study, it would be also interesting to monitor changes in dietary L-Trp provision in relation to stress-related parameters such as serotonin, cortisol and intestinal integrity. From our Dutch-American studies (see: Koopmans et al. in Journal of Animal Science, Volume 84, Issue 4, April 2006: 963–971) is known that supplemental dietary Trp (5 g/kg as fed basis) to piglets increased hypothalamic serotonergic activity, reduced the salivary cortisol response to mixing, improved intestinal morphology, and reduced physical activity 10 d after diet introduction. Consequently, diets containing high Trp levels improved neuroendocrine components of stress and increased gastrointestinal robustness. Besides, adding DDG with solubles to weaner/grower diets presumably influence on the degree of satiety and behavioural/well-being criteria. With friendly greetings. Zdzislaw Mroz

John Htoo, Based on the summary presented, I would like to highlight as correct, the decision of the team of researchers responsible for the work, to have used a suboptimal level of lysine to determine the best tryptophan relationship with lysine. This decision-making is justified by the fact that animals require grams of amino acids per day or phase, not percentage. Thus it can be deduced that the percentage is established based on an expectation of consumption and is adopted because of its practicality. If in the study of the relationship between any essential amino acid with lysine, an optimum level of lysine is used, there is a risk that the animal's feed consumption will be above the estimated, which would result in excess lysine consumption, which would compromise the result, underestimating the relationship. And exactly because of this reality, I think there was a lack of treatment, that is, using lysine in the requirement of the animal with tryptophan at 15% of the lysine, which would be used to prove its deficiency in the test diets.