The objective of this study was to evaluate the effects of low ambient temperature (LAT) and dietary vitamin C (VC) supplementation on pulmonary vascular remodeling (PVR) and the relative expression of hypoxia inducible factor-1α (HIF-1α), vascular endothelial growth factor (VEGF) and its receptor 2 (VEGFR-2) mRNA of lungs in 21-d-old broilers. 400 1-d-old male Cobb broilers were assigned randomly to 4 treatments as follows for 21 d: 1) LAT and a basal diet; 2) LAT and a basal diet supplemented with 1 000 mg kg–1 VC (LAT+VC); 3) normal ambient temperature (NAT) and a basal diet; 4) NAT and a basal diet supplemented with 1 000 mg kg–1 VC (NAT+VC). Each treatment was composed of 10 replicates of 10 birds per replicate. Samples of lung were collected after the broilers were killed at d 21. LAT increased the ratio of vessel wall area to vessel total area (WA/TA, %) and mean media thickness in pulmonary arterioles (mMTPA, %) (P<0.05). Dietary VC supplementation decreased mMTPA (P<0.05), but had no effect on the WA/TA. LAT increased (P<0.05) the relative mRNA expression of HIF-1α, VEGF and VEGFR-2, while adding VC to the diet could decrease (P<0.05) their relative mRNA expression. A significant positive correlation existed between the level of VEGF mRNA expression and the value of WA/WT (P<0.05) or mMTPA (P<0.05). These results suggested LAT resulted in pulmonary vascular remodeling, and the increase of HIF-1α, VEGF and VEGFR-2 mRNA expression, and dietary VC supplementation can alleviate pulmonary vascular remodeling in broiler by affecting these gene expression.

To investigate the effects of dietary supplementation with folic acid on growth performance, hepatic protein metabolism and serum biochemical indices of early-weaned intrauterine growth retardation (IUGR) piglets, 24 male (Duroc× (Landrace×Yorkshire)) weaned (14-d-old) IUGR piglets were randomly divided into 3 treatments with 8 replicates of 1 piglet per replicate. The piglets in each treatment were fed basal diet supplementation with either 0 (control), 5 and 10 mg kg-1 folic acid. The trial lasted for 21 d. Dietary folic acid supplementation reduced average daily feed intake (ADFI) (P<0.05). In addition, the average daily gain (ADG) in 10 mg kg-1 folic acid group was significantly decreased (P<0.01) and the ratio of feed:gain (F/G) increased slightly (P>0.05). Serum folic acid concentration increased (P<0.01) with increasing folic acid inclusion, however, serum homocysteine concentration decreased significantly (P<0.01). Enhanced serum urine nitrogen (SUN) and diminished serum total protein (TP) as well as liver TP content were observed in 10 mg kg-1 folic acid group (P<0.05). Furthermore, the relative mRNA expressions of insulin-like growth factor 1 (IGF-1) and mammalian target of rapamycin (m-TOR) in liver were respectively tended to reduce (P=0.06) and significantly downregulated (P<0.05) in 10 mg kg-1 group, in compared with 5 mg kg-1 group. However, when compared with control group, folic acid supplementation had no significant effect on the mRNA abundance of IGF-1 and m-TOR. The results indicated that supplementation with 10 mg kg-1 folic acid impaired growth performance and hepatic protein metabolism of early-weaned IUGR piglets while 5 mg kg-1 folic acid enriched diet exerted limited positive effects.