Int J Plant Anim Environ Sci 2021; 11 (3): 363-390 DOI: 10.26502/ijpaes.202111 Research Article Nutritional and Immunopotentiating Function of Methionine for Poultry Nour Ramadan1, Houssam Shaib1*, Mohamad Farran1 1Department of Agriculture, Faculty of Agricultural and Food Sciences, American University of Beirut, Beirut, Lebanon *Corresponding Author: Houssam Shaib, Department of Agriculture, Faculty of Agricultural and Food Sciences, America University of Beirut, Riad El Solh 1107-2020, Beirut, Lebanon Received: 04 April 2021; Accepted: 15 April 2021; Published: 13 July 2021 Citation: Nour Ramadan, Houssam Shaib, Mohamad Farran. Nutritional and Immunopotentiating Function of Methionine for Poultry. International Journal of Plant, Animal and Environmental Sciences 11 (2021): 363-390. Abstract This is vital as the immune system prospers As an essential nutrient and a first limiting amino immensely from adequate nutrition, constituting of a acid in several meal-based poultry diets, methionine balanced diet with supplementation of certain (Met) is of rich nutritional value and physiological essential nutrients. Methionine’s immunopotentiating functions. Methionine’s multiple functions include roles include detoxification, increasing humoral but not limited to protein synthesis, feather immune response, stimulation of the phagocytic development, and protection from oxidative stress, activity of leukocyte, triggering serum lysozyme methylation of DNA reactions as well as several activity, and resistance for coccidia infection. These distinct molecules. functions increase immune responses during stress cycles and disease outbreaks in poultry and other Methionine is suggested to play an influential role in animals. Additional research is recommended to both humoral and cell-mediated immune responses. elucidate the role of the host genetic makeup International Journal of Plant, Animal and Environmental Sciences Vol. 11 No. 3 – September 363 Int J Plant Anim Environ Sci 2021; 11 (3): 363-390 DOI: 10.26502/ijpaes.202111 involvement in the relationship between methionine intake; BWG- Body weight gain; FE- Feed and other disease factors. efficiency; EW- Egg weight; EP- Egg production; BW- Body weight; FCR- Feed conversion ratio; Keywords: Methionine; Immunopotentiation; AFP- Abdominal fat pad; AME- Apparent Nutrition; Poultry metabolizable energy; DM- Dry matter; IP- Ideal protein; GI- Gastrointestinal tract; HI- Heat Abbreviations: Met- Methionine; AA- Amino increment; ROS- Reactive oxygen species; AGP- -1 Acid; Arg- Arginine; His- Histidine; Iso- Isoleucine; acid glycoprotein; (IL)-l- Interleukin; LPS- Leu- Leucine; Lys- Lysine; Phe- Phenylalanine; Thr- Lipopolysaccharide; LMI- Leucocyte migration Threonine; Try- Tryptophan; Val- Valine; Pro- inhibition; PHA-P- Phaseolus vulgaris; IgG- Proline; Cys- Cysteine; Gly- Glycine; EAA- Antibody immunoglobulin G; NDV-Newcastle Essential AA; NEAA- Nonessential AA; CEAA- disease virus; Ab- Antibody; SOD- Superoxide Conditionally EAA; FAA- Functional AAs; SAA- dismutase; GSH-Px- Glutathione peroxidase; MDA- Sulfur amino acids; TSAA- Total sulfur amino acids; Malondialdehyde; PHA- Phytohaemagglutinin; CAS- Chemical Abstracts Service; RN- Registry ConA- Concanamycin A; Th- T-lymphocyte helper Number; FDA- US Food and Drug Administration; cells; SRBC- Anti-sheep red blood cell antibody; UNII- Unlicensed National Information CBH- Cutaneous basophilic hypersensitivity; CV- Infrastructure; SAMe- S-adenosylmethionine; MAT Coefficient of variation; HCT%- Hematocrit I- Methionine adenosyl transferase I; MAT II- Methionine adenosyl transferase II; SAH- S- 1. Introduction adenosylhomocysteine; HCys- Homocysteine; Amino acids (AA) are the building blocks of SucCoA- Succinyl-CoA; CAC- Citric Acid Cycle; biological proteins. Over 500 AA exist in nature, TCA-Tricarboxylic acid cycle; MS- Methionine though 20 of which can incorporate into proteins by synthase; BHMT, E.C.2.1.1.5-Betaine-homocysteine arranging in myriad of ways (i.e metabolic proteins, methyltransferase; DLM- D, L-methionine; MHA- structural proteins, enzymes, as well as precursors of FA- L-methionine hydroxy analog-free acid; MHAC- multiple body constituents) serving variety of DL- methionine hydroxyl analog calcium; AAFCO- functions [1-3]. AA obtained from protein are American Feed Control Officials; CFR-Code of utilized by avian species to fulfill a variety of Federal Regulations; FDA- Food and Drug function. Such that, proteins are underlying Administration; BCAA- Branched-chain AA; GMOs- constituent of structural and protective tissues such as Genetically modified organisms; E. coli- Escherichia skin, feathers, ligaments, bone matrix, bone matrix, coli; C. glutamicum- Corynebacterium glutamicum; soft tissues, inclusive of organs as well as muscles ME- Metabolic energy; CP- Crude protein; N- [4]. Nitrogen; NRC- National Research Council’s; ME:CP- Metabolic energy to crude protein ratio; AF- The carbon skeleton of AA categorizes the dietary Abdominal fat; FC- Feed conversion; FI - Feed essentiality of AA [6]. According to the National International Journal of Plant, Animal and Environmental Sciences Vol. 11 No. 3 – September 364 Int J Plant Anim Environ Sci 2021; 11 (3): 363-390 DOI: 10.26502/ijpaes.202111 Research Council’s (NRC), ten out of the twenty-two synthesized by the bird and due to its exceptional AA (arginine (Arg), histidine (His), isoleucine (Iso), emphasis on poultry growth and production [12]. Met leucine (Leu), lysine (Lys), Methionine (Met), is also classified as a FAA. Animals ought to obtain phenylalanine (Phe), threonine (Thr), tryptophan EAA from the diet, however many feed ingredients (Try) and valine (Val) found in body proteins are lack some of the EAA. In a typical corn-soybean classified as the essential AA (EAA) for the nutrient meal, birds’ requirement for fulfilling certain EAA requirements of poultry [4]; that is, they are may fail; this is the case for lysine (Lys), methionine indispensable as their carbon skeleton cannot be (Met), threonine (Thr), and tryptophan (Trp). Met is synthesized de novo by the avian species. In contrast, considered the first limiting AA, with lysine and AA that can be synthesized by the animal are known threonine being the second and third limiting AA as nonessential AA (NEAA) [5-7]. It was assumed respectively in a practical corn-soybean poultry fed that animals do not require NEAA in their diets for diet [13, 14]. maximal nutrition as they are capable of synthesizing adequate quantity of NEAA. Scientific research on When formulating bird diet, sulfur amino acids animal as well as cell culture have nonetheless (SAA) are crucial addition. Met and cysteine (Cys) demonstrated evidence of NEAA carrying critical are the two sulfur-containing AA (SAA); both are the roles in multiple signaling pathways, while further principle providers of organic sulfur within the avian demonstrating the importance of considering AA body and ought to be considered together as total functions beyond their protein synthesis as young sulfur amino acids (TSAA) nutrient requirements animals are unable to synthesize adequate amounts of [15-19]. NEAA particularly during early phase development to support their growth as the rates of utilization are All AA must be present in cell into order for correct relatively greater than rates of synthesis; to poultry protein synthesis to take place. Therefore, it is crucial this is true for Arg and proline (Pro). Such AAs are for protein and EAA to be supplied by the diet, where referred to as conditionally EAA (CEAA) [5, 8-10]. formulating dietary requirements for both ensures the appropriate approach for physiologically required AA Functional AAs (FAA) is rather a notion developed to be implemented [7]. to further define those AAs that regulate and engage in key metabolic pathways to improve health, Met is ought to be available sufficiently in the diet to survival, growth, development, and the reproduction provide the building blocks of tissues, immune cells of organisms. An observed deficiency in FAA and to support the development of feathers [6, 20, whether it be EAA or NEAA hinders both the 21]. Elevated levels of Met exist in eggs, sesame synthesis of protein as well as the species’ body seeds, in addition to Brazilian nuts, fish meal, corn homeostasis [11]. gluten meal, alfalfa meal, as well as sunflower seeds meal [20, 22-24]. Yet, Met is found to be limited in Methionine is an EAA as it cannot be biologically most natural sources of plant protein and it is International Journal of Plant, Animal and Environmental Sciences Vol. 11 No. 3 – September 365 Int J Plant Anim Environ Sci 2021; 11 (3): 363-390 DOI: 10.26502/ijpaes.202111 therefore established as the first limiting AA for Figure 2 below. The liver is the main site of Met broilers and the second limiting AA for laying hens metabolism where Met is the first limiting AA in in a typical corn-soybean meal ration [24]. This commercial poultry [27]. The metabolism of Met is article discusses the effect of immunopotentiation of vital for numerous physiological processes (Figure methionine on broilers by going through methionine 3). Expressly, Met is principally involved in the aid forms, metabolism, deficiency, and toxicity. It also of methyl transfer reactions via its conversion to its shows the nutritional, fast-growing and slow-growing active form as S-adenosylmethionine (SAMe) which requirements in addition to the digestibility and the is achieved by the catalyzation of methionine ideal protein ratio and choosing