[Show abstract][Hide abstract] ABSTRACT: The objectives of this study were to investigate the potential mechanisms of dietary arginine (Arg) and N-carbamoylglutamate (NCG) supplementation on reproductive performance of sows. Twenty-seven crossbred (Landrace×Large White) sows with similar body weight and parity at day (90±1) of gestation were assigned randomly into 3 groups (n=9) control group, Arg group, NCG group, and fed with the following diets: a control diet, and the control diet supplemented with 1.0% Arg or 0.1% NCG. Litter size was recorded. Blood samples were obtained for biochemical analyses. Placenta chorioallantoic membrane tissue collected immediately after birth to preserve in RNA stabilizer for mRNA analysis of endothelial nitric oxide synthase (eNOS), endothelial growth factor a (VEGFA) and placenta growth factor 1 (PlGF1) by real time-PCR. The results showed that compared with the control group, the average birth weight of all piglets born alive were 16.2% and 14.3% higher in the Arg and NCG groups (P<0.05), respectively; plasma VEGFA was higher in the Arg group (P<0.05). The expression of VEGFA in the allantochorion tissue of the NCG-supplemented group was higher (P<0.01), and tended to be higher in the Arg-supplemented group (0.05<P<0.1). NCG significantly increased protein concentration of PlGF1 in plasma (P<0.05), and enhanced PlGF1mRNA expression in allantochorion tissue of placenta (P<0.01). The results suggested that dietary Arg and NCG supplementation play important roles in meliorating placental vascular function and promoting the nutrients supply to fetus.
[Show abstract][Hide abstract] ABSTRACT: Placental vascular formation and blood flow are crucial for fetal survival, growth and development, and arginine regulates vascular development and function. This study determined the effects of dietary arginine or N-carbamylglutamate (NCG) supplementation during late gestation of sows on the microRNAs, vascular endothelial growth factor A (VEGFA) and endothelial nitric oxide synthase (eNOS) expression in umbilical vein. Twenty-seven landrace×large white sows at day (d) 90 of gestation were assigned randomly to three groups and fed the following diets: a control diet and the control diet supplemented with 1.0% L-arginine or 0.10% NCG. Umbilical vein of fetuses with body weight around 2.0 kg (oversized), 1.5 kg (normal) and 0.6 kg (intrauterine growth restriction, IUGR) were obtained immediately after farrowing for miR-15b, miR-16, miR-221, miR-222, VEGFA and eNOS real-time PCR analysis. Compared with the control diets, dietary Arg or NCG supplementation enhanced the reproductive performance of sows, significantly increased (P<0.05) plasma arginine and decreased plasma VEGF and eNOS (P<0.05). The miR-15b expression in the umbilical vein was higher (P<0.05) in the NCG-supplemented group than in the control group. There was a trend in that the miR-222 expression in the umbilical vein of the oversized fetuses was higher (0.05<P<0.1) than in the normal and IUGR fetuses. The expression of eNOS in both Arg-supplemented and NCG-supplemented group were lower (P<0.05) than in the control group. The expression of VEGFA was higher (P<0.05) in the NCG-supplemented group than in the Arg-supplemented and the control group. Meanwhile, the expression of VEGFA of the oversized fetuses was higher (P<0.05) than the normal and IUGR fetuses. In conclusion, this study demonstrated that dietary Arg or NCG supplementation may affect microRNAs (miR-15b, miR-222) targeting VEGFA and eNOS gene expressions in umbilical vein, so as to regulate the function and volume of the umbilical vein, provide more nutrients and oxygen from the maternal to the fetus tissue for fetal development and survival, and enhance the reproductive performance of sows.