Effects Of Potassium Diformate On The Growth Axis & Hepatic Gluconeogenesis In Weaning Piglets

The objective of this study was to determine the effects of potassium diformate (KDF) and antibiotics on growth axis in weanning piglets. A total of 270 piglets (Landrace and large white crossbreed) weaned at 28d of age were allocated randomly into three groups, with 6 replicates in each group and 15 piglets in each replicate. Group 1 (negative control) were fed basal diet, without any antibiotic or acidifier, group 2 (positive control) were fed basal diet supplemented with antibotics (16.6 mg/kg colistin sulfate plus 45 mg/kg kitasamycin and 83mg/kg olaquindox), and group 3 (treatment group) were fed basal diet plus 1% KDF. This study through short-term feeding (1 week) and long-term feeding (5 weeks) investigated:(1) The effects of KDF on growth performance and blood biochemical indices in weaning piglets; (2) The effects of KDF on the genes expression raleted with growth axis in weaning piglets; (3) The influence of KDF on the expression of hepatic gluconeogenic genes in weaning piglets.1 Effects of KDF with short-term feeding on the growth axis and hepatic gluconeogenesis in weannig piglets1.1 Growth performance and blood biochemical indicesAs compared with the basal diet group, KDF treatment did not change the finial weight (FW), average daily bodyweight gain (ADG), average daily feed intake (ADFI) and feed conversion ratio (FCR). There were no remarkable difference in blood indices level of high density lipoprotein (HDL), low density lipoprotein (LDL), total cholesterol (TC), triglyceride (TG) and blood glucose (BG) in plasma between the basal diet group and KDF group.KDF group had a lower F/G than antibiotics group (P=0.010). KDF treatment significantly improved the level of BG (P=0.000), whereas significantly decreased the blood indices level of HDL (P=0.018), TC (P=0.006) and LDL (P= 0.035). KDF treatment did not change the level of TG.The antibiotics group did not influence growth performance on weaning piglets, Antibiotics group significantly increased the blood level of HDL (P=0.009) and TC (P=0.001), whereas markedly decreased the level of BG (P=0.001) compared with the basal diet group. There was no remarkable difference in the level of LDL and TG between antibiotics and the basal diet group.1.2 The genes expression of growth axisAs compared with the basal diet group, KDF treatment significantly increased the abundance of growth hormone (GH) mRNA (P=0.050) in pituitary, and the mRNA of insulin-like growth factor-1 (IGF-1) (P=0.014) in liver. The mRNA expression of growth hormone releasing hormone (GHRH), somatostatin (SS), growth hormone receptor (GHR) and insulin-like growth factor-1 receptor (IGF-1R) in hypothalamus, the level of GHR and IGF-1R mRNA in pituitary, and the mRNA of GHR and IGF-1R were no remarkable difference between the two groups.As compared to the antibiotics group, KDF group had lower expression of SS mRNA (P=0.002) in hypothalamus, the abundance of IGF-1R (P=0.049) in liver. KDF did not change the mRNA expression of GHRH, GHR and IGF-1R in hypothalamus, GH, GHR and IGF-1R in pituitary, and IGF-1 and GHR in liver.As compared with the basal diet group, antibiotics group significantly increased the mRNA level of SS (P=0.013) in hypothalamus, the mRNA expression of IGF-1 (P=0.028) in liver, whereas markedly decreased the mRNA expression of IGF-1R (P=0.041) in pituitary. The mRNA level of GHRH, IGF-1R and GHR in hypothalamus, GH and GHR in pituitary, and GHR and IGF-1R in liver were not affected by antibiotics group.KDF group and antibiotics group did not change the content of hepatic IGF-1 compared with control group.1.3 The genes epression of hepatic gluconeogenesisAs compared with the basal diet group, KDF treatment dramaticly decreased the mRNA expression of fructose-1,6-bisphosphatase (FBP1) (P=0.022), phosphoenolpyruvate carboxykinase (PCK1) (P=0.049), and 11β-hydroxysteroid dehydrogenase type 1 (11β-HSD1) (P=0.001) in liver. The mRNA expression of glucose-6-phosphatase (G6PC) and pyruvate carboxylase (PC) were no differene between the two groups.As compared to the antibiotics group, KDF had lower mRNA expression of G6PC(P=0.003), PCK1 (P=0.020), PC (P=0.001), FBP1 (P=0.003) and 11β-HSD1(P=0.027) in liver.As compared with the basal diet group, the antibiotics group significantly increased the mRNA level of G6PC (P=0.040) and PC (P=0.003) in liver. There was no difference in PCK1, FBP1 and 11β-HSD1 in liver between the basal diet and antibiotics groups.2 Effects of KDF with long-term feeding on the growth axis and hepatic gluconeogenesis in weaning piglets2.1 Growth performance and blood biochemical indicesAs compared to the basal diet group, KDF group significantly improved the finial weight (P=0.001), ADG (P=0.004) and ADFI (P=0.027), whereas significantly decreased F/G (P=0.022) in weaning piglets. The level of HDL, TC, LDL, TG and BG were not changed by KDF group.As compared to the antibiotics group, KDF treatment had higher fininal weight (P=0.027) and ADG (P=0.030), whereas significantly decreased F/G (P=0.045). The level of HDL, TC, LDL, TG and BG were not affected by KDF group.As compared to the basal diet group, the antibiotics group was no difference in the fininal weight, ADG, ADFI and F/G, and the level of HDL, TC, LDL, TG and BG did not changed in plasma.2.2 The genes expression of growth axisAs compared with the basal diet group, KDF group markedly upregulated the mRNA expression of GH (P=0.003) in pituitary, the level of IGF-1 (P=0.000) and GHR (P=0.012) in liver. KDF group did not influence the mRNA expression of GHRH, SS, IGF-1R and GHR in hypothalamus, the abundance of GHR and IGF-1R in pituitary, and the level of IGF-1R in liver.As compared with the antibiotics group, KDF significantly increased the mRNA level of GH (P=0.003) in pituitary, IGF-1 (P=0.001) and IGF-1R (P=0.009) in liver. There was no difference in the mRNA expression of GHRH, SS IGF-1R and GHR in hypothalamus, the level of GHR and IGF-1R in pituitary, and the abundance of GHR in liver.As compared with the basal diet group, the antibiotics group did not change the expression of GHRH, SS, IGF-1R and GHR in hypothalamus, the level of GH, GHR and IGF-1R in pituitary, and the abundance of IGF-1, GHR and IGF-1R in liver.KDF group and antibiotics group significantly increased the content of hepatic IGF-1 compared to the control group (P=0.002,0.001).2.3 The genes epression of hepatic gluconeogenesisAs compared to the basal diet group, KDF treatment had higher mRNA expression of G6PC, PCKland FBP1 (P=0.001,0.049,0.021) in liver. There were no remarkable difference in the mRNA level of PC and 11β-HSD1 in liver between the basal diet group and the KDF group.As compared to the antibiotics group, KDF significantly increased the mRNA level of G6PC and FBP1 (P=0.040,0.008) in liver. There was no notable difference in the mRNA expression of PCK1, PC and 11β-HSD1 in liver between two groups.As compared to the basal diet group, the antibiotics group did not affect the hepatic G6PC, PCK1, PC, FBP1 and 11β-HSD1 mRNA expression.Above data suggested, (1) KDF could improve the growth performance and upregulate the mRNA expression of hepatic IGF-1. (2) The regulation of hepatic gluconeogenesis with feeding KDF may be related with the age of weaning piglets and the role of the duration of KDF.