OH-Methionine and DL-Methionine are similar in sustaining laying performance and egg quality of Babcock layers

Dear Martin Smith

Thank you very much for your question. For you and those interested in the feed composition and additional details on the design, please find out more here https://en.engormix.com/poultry-industry/articles/similar-laying-hens-performance-t44946.htm

Kind regards,

Juarez Donzele - While I agree that a true Negative Control is the halmark of good experimental desing, this study appears to have been more of a practical field trial, wherein multiple diets can be very hard to accomodate without introducing other problems. I think Martin's comments about other nutrients being first limiting is a more significant concern in this case.

From the broiler literature, there is evidence that bioequivalence of DL-methionine and the hydroxy-analog can be manipulated by where on the dose response curve the comparison is made. Using common intercept methods (Similar to the 3 point design you propose), DL-methionine is pretty consistently shown to be superior on a molar basis to the analog. However, comparisons closer to practical application levels (ie arround requirement) tend to show no difference or occasionally supperior performance from the analog as compared with DL-methionine. This is most clearly presented in the work of Kratzer and Littell (2006)

Kratzer, D. D., and R. C. Littell. 2006. Apropriate statistical methods to compare dose response of methionine sources. Poult. Sci. 85:947-954.