Avaliação de níveis e fontes de metionina sintética no desempenho e expressão de genes do metabolismo e transportadores jejunais em frangos

Abstract

Methionine is an essential amino acid for poultry, being the first limiting amino acid in commercial broiler diets, along with cysteine. The metabolic processes of sulfur amino acids generate fundamental metabolites for several physiological processes, such as the synthesis of body tissues, antioxidative functions, cell division, taurine production, activation of mTORC1 and regulation of the expression of genes involved in the metabolism of birds. For methionine supplementation in deficient diets, DL-Methionine (DL-Met) or DL-Methionine Hydroxy Analogue (DL-HMTBA) is usually used, these have different chemical and physical structures, interfering with absorption and subsequent metabolism. Therefore, a systematic review was initially carried out in order to present an overview of the studies that evaluate the influence of supplementation with sulfur amino acids using DL-Met, DL-HMTBA or L-Met, on gene expression in broiler chickens. For this, a complete search was performed in electronic databases, using a combination of words by the PICo method (Population, Interest and Context) with terms related to broiler chickens, methionine and gene expression. The search was carried out in the Scopus, Web of Science and PubMed databases through the collection of the CAPES Periodicals Portal. The resulting articles were exported to a reference management program and subjected to various selection criteria, which ranged from a total of 596 to 15 articles. From the review it was possible to obtain an overview of the studies that evaluated gene expression in broiler chickens. With this, an experiment was carried out with the objective of evaluating the effects of DL-Met and DL-HMTBA in three levels of supplementation in the performance, expression of genes of the metabolism of sulphurous amino acids and expression of methionine transporters. For this, 450 chicks were distributed in a completely randomized design in a 2x3 factorial scheme, with two sources of methionine (DL-Met and DL-HMTBA) and three levels of supplementation (deficiency, requirement and excess), totaling 6 treatments with 5 replications. of 15 birds each. The experiment was carried out at the Poultry Laboratory of the Center for Human, Social and Agrarian Sciences, Campus de Bananeiras/UFPB. The evaluated parameters were: weight gain (g), feed intake (g), feed conversion (g/g), mRNA expression of genes (MAT1, MTR, BHMT, MTRR, CBG and GSS), mRNA expression of glucose transporters (SGLT1, GLUT2 and GLUT5), and mRNA expression of methionine transporters (SAT1, SAT2, SAT3, ATB0,+, y+LAT1, y+LAT2, LAT1, B0AT, b0,+AT and rBAT) in the jejunum of broilers. DL-HMTBA increased the expression of BHMT (p=0.0072) and MTRR (p=0.0003) in the jejunum of birds. Methionine deficiency increased the expression of BHMT (p=0.0805) and MTRR (p=0.0018). Higher GSS expression was observed in birds that were supplemented with DL-HMTBA (p=0.0672). Birds fed with DL-HMTBA showed worse weight gain (p=0.0117) and higher feed conversion (p=0.0170); methionine deficiency resulted in higher feed intake (p=0.0214), lower weight gain (p<0.0001) and consequently higher feed conversion (p<0.0001). The use of DL-HMTBA increased the expression of SGLT1 (p=0.0065), SAT1 (p=0.0167) and y+LAT2 (p<0.0001). Methionine deficiency resulted in increased expression of SGLT1 (p=0.0004), GLUT5 (p=0.0001), SAT2 (p=0.0064), y+LAT2 (p=0.0677) and rBAT (p =0.0800). The use of DL-Met increased LAT1 expression (p=0.0420). It is preferable to carry out sulfur amino acid supplementation with DL-Met at the requirement and DL-HMTBA above the requirement.