ARTICLE FEED & ADDITIVE MAGAZINE April 2024 61 nitrogen group. Formulating with OH-Methionine to match the methionine requirements, without assigning any CP level, will negatively impact the feed formula optimization. This is because the formulation system will compensate for its CP level using other protein sources, with consequent feed cost increase. To address this, ADISSEO recommends applying the equivalent CP level of 51.7% for Rhodimet AT88, calculated considering the 88% of CP level of the DL-Met form. USE OF RECOMMENDED ENERGY VALUE FOR OH-METHIONINE IN FORMULATION A specific analysis must be done while evaluating both Metabolizable (ME) or Net Energy (NE) of the various methionine sources. To assign the energy value of any product, we start with determination of Gross Energy (GE), the intrinsic energy that turns into heat. Considering the complete digestibility of all crystalline amino acids, their Digestible Energy (DE) is 100% and then equal to the GE. After fixing these, we can calculate the ME deducting from the GE/DE the fraction lost via the urine. But why do different methionine sources have variable ME-NE levels? It is well known that all methionine sources are used by animals after being metabolized into L-Methionine form, however each of them will have their specific metabolic pathways. Since OH-Methionine has a different metabolic pathway rather than L-Met/DL-Met, this will result in a different ME and NE level. The detailed metabolic pathways and consequent determination of ME and NE levels were explained in a recent published paper (Van Milgen et al. 2019). Briefly OH-Methionine has a NH2 sparing effect, by recycling an amino group derived from other amino acids in excess. This will prevent the excretion of these amino groups in excess under uric acid that lead to energy savings. CONCLUSION Applying the appropriate nutritional matrix for methionine sources will result in feed cost optimization, by optimizing complete feed crude protein & energy values (metabolizable or net energy). Due to its nutritional and molecular values and its relative cost, OH-Methionine is the best option while formulating optimal diets, especially when its validated matrix is completely applied. On average considering a price ratio of 88/99% for the OH-Met and DL-Met, applying the full matrix values will allow a cost saving of about 0.30 €/ton of typical broiler feed. Considering the inclusion rate of 3 kg/ton, this means a benefit of 0.10 €/kg OH-Met applied. All other savings will be extra benefits for the feed producers. Literature available upon request. About Nicola Tallarico Nicola Tallarico graduated as an agriculture engineer at the University of Bologna in 1995 and completed the Ph.D in zootechnical science at University of Milan in 2001. After graduating, Tallarico started to cooperate with the Department of Poultry Science of the University of Bologna, during which followed various nutritional studies with more than 30 scientific papers published. In 2003, Nicola Tallarico joined an Italian company specialized in encapsulation technologies as technical-sales manager, and after the acquisition of this unit by a multinational company, Nicola joined them and moved to Belgium in 2010. Here he acts as Technical Service and Product Manager for technological additives, and in the last period as Regional Director for the EMENA regions. At the beginning of 2022, Tallarico joined Adisseo as Global Category Manager for the Methionine Units, sharing his technical knowledge with the global market. About Tahir Mahmood Tahir Mahmood completed his Ph.D. in poultry nutrition from University of Agricultura Faisalabad, Pakistan in 2017 followed by a Post doctorate in poultry nutrition from China Agricultural University. He joined amino acid research team of Adisseo in 2020 as amino acid research scientist. In Adisseo, his main research interests are amino acids nutrition and successful development of low protein diets for poultry. In his current role, he collaborates with leading experts from both academics and industry. Mahmood regularly publishes peer-reviewed articles on various topics in leading journals of poultry nutrition. He is originally from Pakistan and is based in Lyon, France.
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