Effects of phenylalanine supplementation on meat fatty acid composition, gut microbiota, and pork volatile organic compound profile in finishing pigs

Abstract Background Pork quality is a crucial factor influencing consumer purchasing decisions. Previous research has indicated that dietary amino acids such as lysine, arginine, and tryptophan can significantly affect meat quality in finishing pigs. However, the role of phenylalanine, an essential amino acid, in influencing meat quality has not been fully clarified. Results In this study, we investigated the effects of increasing dietary phenylalanine/lysine (P/L) ratios on meat quality using castrated finishing barrows. The results showed that dietary P/L ratios of 0.75, 0.90 and 1.05 did not affect carcass traits compared with the control ratio of 0.60 ( P > 0.05). Pigs fed a diet with a P/L ratio of 0.75 exhibited a significant increase in meat a * value at 45 min postmortem ( P = 0.01), along with alterations in fatty acid profiles and gut microbiota compositions. PICRUSt2 analysis revealed that the fatty acid metabolic pathway was significantly enriched in predicted functional potential of the gut microbiota under the 0.75 P/L treatment, and Coprococcus , Lachnospiraceae_NK4B4_group , and Dialister were significantly correlated with muscle fatty acid profiles ( P < 0.05). Furthermore, the PLSR analysis showed that muscle C8:0, C10:0, and C24:1 were negatively correlated with pork volatile organic compounds (VOCs). Conclusions This study demonstrated that dietary P/L ratios affected gut microbiota composition in castrated finishing barrows, as well as meat color, fatty acid composition, and free amino acid profiles of pork. Moreover, fatty acids (specifically C8:0, C10:0, and C24:1) correlated with gut microbiota and were associated with differences in the VOC profile between the 0.75 and 0.60 P/L ratio groups.