Eight hours after the last feeding, blood samples were
collected through the anterior vena cave puncturein to
10 mL heparin-free Vacutainer tubes. Blood was
centrifugated at 3500×g for 5 min to obtain serum,
which was stored at -20 ℃ until analysis for antioxidant
parameter. One pig from each pen (per group: two gilts
and two barrows) was selected randomly to be killed by
exsanguinations after electrical stunning. Carcass
characteristics and meat quality were detected. Part of
the longissimus muscle was removed and quickly frozen
in liquid nitrogen, and then stored at -80 ℃ until the
extraction of DNA and RNA.