Abstract
This study aimed to investigate the effects of dietary valine/isoleucine (V/I) ratio and slaughter weight on the profile of pork flavor precursors. Metabolomics and volatilomic profiling were performed on meat harvested from a 2 × 2 factorial feeding study. Thirty-six Duroc × Landrace × Yorkshire castrated male pigs with around 75 kg body weight (BW) were randomly allocated to two dietary treatments, involving V/I (1.23 and 2.60 at 75 to 100 kg BW, 1.24 and 2.39 at 100 to 135 kg BW for the normal dietary valine/isoleucine ratio defined N [V/I] and high dietary valine/isoleucine ratio defined H [V/I], respectively) and two slaughter weights (lower weight [LW] 100 kg and higher weight [HW] 130 kg). Each group consisted of six replicates of three pigs per replicate. The trial lasted for 63 d. Dietary V/I significantly affected several metabolic pathways in muscle, including alanine, aspartate and glutamate metabolism, fructose and mannose metabolism, and amino sugar and nucleotide sugar metabolism. On the other hand, contents of acylcarnitine (ACar; P < 0.001) and lysophosphatidylethanolamine (LPE; P = 0.036) were significantly higher in the meat of the HW pigs than those of the LW pigs. Among 48 volatile organic compounds (VOCs) identified in pork, the concentrations of seven VOCs were altered by dietary V/I, that of 17 VOCs by slaughter weight, and acetoin and 1-heptanol by both factors (P < 0.05). In addition, increased dietary V/I altered 53 hydrophilic compounds and 10 VOCs in LW pigs, and altered 39 hydrophilic compounds and six VOCs in HW pigs (P < 0.05). In conclusion, the increased dietary V/I significantly altered flavor precursors of pork, but this effect decreased as the slaughter weight increased.