Increased Inclusion of Dietary Methionine Sources Improves Pork Quality in Association with the Regulation of Energy and Protein Metabolism and Muscle’s Fiber Profile

Abstract

Background Intensive selection for faster growth rate and higher lean percentage led to increase in protein deposition but deterioration in meat quality of pigs, thus there is growing interest in exploring the nutritional strategies to improve meat quality. Methionine has been shown to activate mechanistic target of rapamycin complex 1 protein kinase that plays pivotal roles in the regulation of protein and lipid synthesis. However, few study reports are available regarding the effects of dietary methionine supplementation at levels beyond growth requirements on lipid and protein metabolism and thus on pork quality. The objective of this study was to assess whether pork quality was improved by increasing dietary digestible sulfur amino acids (SAA) levels, with pigs fed the control (100% SAA), DL-Methionine (125% SAA)- or OH-Methionine (125% SAA)-supplemented diets during 11–110 kg period. Results Increasing SAA above requirements did not significantly affect growth performance, whereas improved pork quality as indicated by the decreased drip loss and a tendency towards decrease in shear force of longissimus lumborum muscle. Moreover, fresh muscle from barrows fed OH-Methionine showed a higher lightness value compared with the control and DL-Methionine treatments. The relatively lower shear force might be explained by the decrease in crude protein and increase in glycolytic potential, while the decreased drip loss was associated with down-regulation of genes (like fast glycolytic IIx) regulating fiber types. The increased lightness value of fresh muscle from barrows fed OH-Met diets appeared to be associated with the increased lactate level, which can be further explained by the increased plasma short-chain fatty acids concentrations, up-regulated G-protein coupled receptor 43 activation and enhanced glucagon-like peptide 1 secretion. Conclusion Increased SAA consumption appeared to improve pork water-holding capacity and tenderness likely through regulation of energy and protein metabolism and muscle’s fiber profile, which provides new insights into the nutritional strategies to improve meat quality.