Relative Bioavailability of DL and L-Methionine in Broilers

Dr Valeriy Kryukov, considering his reports and that, in several regions of the globe, the incidence of mycotoxins in the ingredients normally used in the preparation of feed for poultry and pigs is high, the use of DL-methionine may provide a better result compared to L- methionine. And that, this pattern of result would be more consistent in farms with a low level of health challenge in which the use of drugs is restricted. Is this reasoning logical?

Dear Dr. Garcia and Khan. It looks to me that a large part of the difference in the availability values calculated come not from the fact that the responses with L-Methionine were much better than with DL but that the analysed values of L-Methionine are on average lower. Since the regressions used analysed values, this contributes in large part to the better RBVs observed. There's nothing wrong in doing it this way but other researchers consider that if the analysed values come quite close to the expected ones they prefer to use expected values. The reason is that analysed values carry differences due to sampling and analysis and, considering the purity of the two sources used (at least 99%), using analysed values assume that an error in weighing was made (much more difficult to happen under experimental circumstances). I wonder what the RBVs would be if you use expected values in the regression analysis.

Hi, Many Thanks MR ENG ALI AFSAR./

Dear Enric Esteve - Garcia and Daulat Rehman Khan! I have not studied the comparative biological efficacy of L and DL-methionine. I conducted research for a different purpose and found that DL-methionine induces cytochrome P-450.This indicates the activation of the xenobiotic metabolism system. I conclude that D-methionine has xenobiotic properties. Based on this, some of it will be metabolized as a foreign substance, and this is indisputable. This can be confirmed in experiments on feeds that do not contain xenobiotics, including medications, mycotoxins and other substances. As for practical poultry farming, D,L-methionine can better affect productivity, since it induces the xenobiotic metabolism system, creating the body's defense against foreign substances, including mycotoxins. However, the drug doses will have to be increased

When I was associate Prof. at University of Pretoria, one of my students conducted a detailed literature review of 244 peer reviewed published papers comparing the digestive, metabolic and biological differences in L-Methionine vs. DL Methionine. This Review of 244 peer reviewed published papers would support L Met to be more beneficial as a synthetic source of methionine than D-Met or DL-Met in broilers and piglets in terms of: - Improved L-Met absorption in the small intestine - Better supply of L-Met at tissue for protein synthesis - Less catabolism / excretion of Met break down products - Lower oxidative stress to the animal - Significant benefits in young animals from day-old - Improved biological performance (BW gain and FCR) in 73% -76% of all published studies - The studies that showed no difference in performance had a compromised experimental design / did not start the study at day-old when differences are greatest.

Dear Enric Esteve-Garcia et al why did you chance Anticoccidial ? Best regards

I will like to know if breeds of Broiler had any influence on the published literature review between the Dl and L meth ? Secondly what was the result of the comparison on the other experiments above day old age ( Probably from.groer stage ) ? Regards