The Correlation between Plasma L-carnitine and Growth Performance in Suckling Pigs in Respect of mRNA Expression of a Carnitine Transporter, OCTN2, in Lactating Porcine Mammary Tissues

Two objectives of this study were to investigate the weekly change in plasma L-carnitine concentration during the 28 day suckling period and to determine the relative mRNA expression level of a L-carnitine transporter, OCTN2, in porcine mammary tissue at early and peak lactation. The results showed that the L-carnitine concentration of piglets after giving birth was 3.94±0.13 mg/L. L-carnitine levels on day 7 were significantly decreased (p<0.05) compared to those on the 1 day. On day 14, L-carnitine level increased significantly (p<0.05) to the concentration of 3.99±0.55 mg/L and maintained this level until weaning day. As with the increase in plasma L-carnitine concentration 1 week following suckling age, the body weight also increased significantly (p<0.05). The linear correlation of suckling ages and L-carnitine levels has a significant and positive correlation (R Adj =0.1328, p<0.05). The mRNA expression of OCTN2 found in these lactating sow mammary tissues showed the relative abundance of this carnitine transporter. It tended to be decreased in lactating mammary tissue of sows at their peak compared to those at early lactation (p=0.065). Therefore, the significant change or maintenance in plasma L-carnitine concentration and body weight gain during suckling period provided an insight into the effects of L-carnitine in suckling piglets. Additionally, the mRNA expression of OCTN2 in the lactating mammary cells will be further investigated in cellular and molecular regulatory mechanisms to transport L-carnitine from dams to their piglets via the mammary glands.