Effects of dietary l-methionine supplementation on the growth performance, carcass characteristics, meat quality, and muscular antioxidant capacity and myogenic gene expression in low birth weight pigs.

The aim of the present study was to investigate the effects of dietary Met supplementation on the growth performance, carcass characteristics, meat quality, and muscular antioxidant capacity and myogenic gene expression in low birth weight (LBW) pigs. Thirty normal birth weight (NBW) and 60 LBW female piglets were selected at birth. In each litter, after weaning, 1 of the LBW piglets (LBW-CON group) and 1 of the NBW piglets (NBW-CON group) were fed the basal diets and 1 LBW littermate was fed the basal diet supplemented with Met (LBW-MET group). Thus, all pigs were distributed into groups of 3 treatments × 6 replicates (pens) × 5 piglets per replicate up to 180 d of age. Compared with NBW-CON pigs, LBW-CON pigs had decreased ADG ( = 0.004) and ADFI ( < 0.001) during the postweaning period and greater backfat thickness ( = 0.015) at slaughter. In addition, LBW-CON pigs exhibited compromised meat quality, as evidenced by a greater drip loss at 24 h postmortem( = 0.037) and a lower pH at 45 min postmortem ntents of malondialdehyde (MDA; = 0.046) and protein carbonyl ( = 0.028) in the LM. The LBW pigs fed the Met-supplemented diets had a greater amount of reduced glutathione (GSH; = 0.009) but a lower level of MDA ( = 0.015) in the LM compared with the LBW-CON pigs. Methionine supplementation increased the pH at 24 h postmortem (pH) value ( = 0.004) but reduced the drip loss at both 24 ( = 0.016) and 48 h ( = 0.005) postmortem of LBW-MET pigs in comparison with the LBW-CON pigs. The Met-supplemented diets increased the -adenosyl-methionine content ( = 0.006), DNA methyltransferase activity ( = 0.007), and CpG methylation levels of the sites +27 ( = 0.008) and +160 ( = 0.009) of myostatin (MSTN) exon 1 but decreased the mRNA expression of MSTN ( = 0.011) in the LM of the LBW-MET group compared with the LM of the LBW-CON group. Additionally, when compared with the LBW-CON group, the area of LM ( = 0.037) was significantly increased in the LBW-MET group, in parallel with the upregulated mRNA abundance of myogenin ( = 0.025), myocyte enhancer factor 2A ( = 0.036), and myocyte enhancer factor 2D ( = 0.015). In conclusion, Met supplementation increases pH and decreases drip loss in the LM of LBW-MET pigs, along with a greater GSH content but a lower MDA accumulation. Also, the LBW-MET pigs showed a greater LM area, which may be associated with the improved expression of myogenic genes.