Globally, across all treatments, values increased between 21 and 56 d of age (P < 0.05), but this effect was more pronounced in S−P− piglets (up to 1.16 ± 0.09 µM) than in other treatment groups (0.71 ± 0.09 µM; sow treatment × piglet treatment × age postweaning; P < 0.05). Vitamin B12 is an enzymatic cofactor of methylmalonyl-CoA mutase, which catalyzes the isomerization of methylmalonyl-CoA to succinyl-CoA (Stroinsky and Schneider, 1987).