Effect of methionine supplementation on mitochondrial genes expression in the breast muscle and liver of broilers

This study aimed at evaluating the expression of the mRNA of avian uncoupling protein (avUCP), of adenine nucleotide translocase (ANT), and of cytochrome c oxidase subunit III (COX III), as well as the performance of broilers fed diets containing two sources and two levels of industrial methionine. Broilers between 22 and 42 days of age were distributed into five treatments (basal diet, supplementation of 0.08% dl-methionine, 0.24% of dl-methionine, 0.11% of MHA-FA and 0.33% of MHA-FA). At the end of the experimental period, birds were sacrificed by neck dislocation and their liver and breast muscle were collected for total RNA extraction. The cDNA was amplified using primers specific for the target genes, and expression was analyzed using the real-time polymerase reaction (qRT-PCR). Methionine supplementation promoted better performance, with the second level (0.24%) of dl-methionine promoting the best results for weight gain. The mRNA avUCP concentration was significantly lower in the muscle of birds fed methionine-supplemented diets, independently of source or level. The highest mRNA avUCP expression was obtained with the basal diet, which also resulted in the worst feed efficiency. The expression of mRNA avUCP in the liver and of mRNA COX III and mRNA ANT in the liver and in the muscle was not influenced by methionine supplementation. Methionine supplementation promotes better broiler performance, and the most efficient birds were fed second level of supplementation of both sources, part of these results may be due to the lower expression of avUCP mRNA in the muscle, which was also lower in birds fed diets with higher amounts of methionine.