Effects Of Diet With Different Concentrate Roughage Ratio On Hepatic Gluconeogenesis In Dairy Goats And Its Mechanism

In this study, effects of diet with different concentrate roughage ratio on hepatic gluconeogenesis and its mechanism were investigated by in vitro, in vivo and hepatic chronic multi-catheter experiments in dairy goats.1. Effect of diet with different concentrate roughage ratio on rumen digestion and metabolism in vitroIn this experiment, three adult multiparous dairy goats, which were installed permanent rumen fistulae by surgical operation, were used as donators of rumen liquid, in order to evaluate effect of diet with different concentrate roughage ratio on rumen digestion and metabolism in vitro. Two types of diets were fed, which were4:6and6:4with different forage to concentrate ration. Two repeats was carried out at every level. The pH value and concentrations of NH3-N,MCP and VFA in rumen liquid were determined at0h,1h,2h,4h,6h,8h and10h respectively. The results indicated that a decline of pH happened in both groups and pH in high-concentrate diet decreased more; As to VFA, high-concentrate diet enhanced the concentrations of acetic acid,propionic acid and butanoic acids,and reduced the ratio of acetic acid/propionic acid,compared with the group of low-concentrate diet.The concentration of NH3-N in both group increased,compare with the group of low-concentrate diet,the concentration of NH3-N was higher in the group of high-concentrate diet. The concentration of MCP in high-concentrate diet was higher.The results showed that the high-concentrate diet could promote generation of propionic acid.2. Effect of diet with different concentrate roughage ratio on rumen digestion and metabolismIn this experiment,eight adult multiparous dairy goats,which were installed permanent rumen fistulae by surgical intervention were used to find the effect of diet with different concentrate roughage ratio on rumen digestion and metabolism in vivo with crossover trial.The pH value and concentrations of NH3-N,MCP and VFA in rumen liquid were determined. The results indicated that a decline of pH happened in both groups and pH in high-concentrate diet was lower, the pH value in both groups was between6.10～7.1;The concentration of NH3-N in the group of high-concentrate diet was higher than the low group at every determined hour,and the curve of concentration in both groups were stable;The concentration change of MCP in both groups were coincidence,reached the highest level at4h and then did not change obviously,which rose earlier and then descended.The concentration of MCP in the group of high-concentrate diets is higher than the low group;As to VFA, the concentration change of acetic acid in both group were coincidence,which rose earlier and then descended with going to calm.The concentration of acetic acid in low-concentrate diet group rose more and was higher than the high group;The concentration change of propionic acid in both groups were coincidence, which rose earlier and then descended.The concentration of propionic acid in high-concentrate diet rose more and was higher than the low group;The concentration change of butanoic acid in both groups were stable;The concentration of butanoic acid in high-concentrate diets group was higher than the low group.The results showed that the high-concentrate diets could promote ferment for abundant propionic acid and supply precursor for hepatic gluconeogenesis to promote energy metabolism.3. Effect of diet with different concentrate roughage ratio on hepatic gluconeogenesis in dairy goatsIn this experiment,four adult multiparous dairy goats, which were installed chronic portal, hepatic vein and femoral artery multi-catheters for vivo trial.Feed two types of diet, which were4:6and6:4with different forage to concentrate ration.The trial was crossover trial.To collect blood in portal,hepatic vein and femoral artery at0h、2h、4h、6h and8h,which was used to determind the concentration of VFA and glucose content in portal and hepatic vein. For the purpose to find the effect of diets with different concentrate roughage ratio on hepatic gluconeogenesis.The results indicated that every acid concentration of VFA in portal,hepatic vein and femoral artery rose gradually after ingestation,reached the highest value at2h and then descended to the incipient level.Propionic acid in hepatic vein and femoral artery was lower.High-concentrate diet enhanced the concentrations of acetic acid, propionic acid and butanoic acids in portal, hepatic vein and femoral artery.Propionic acid increased more than acetic acid in portal vein.The value of acetic acid/propionic acid in both groups rose earlier and then descended,however, the value in the group of high-concentrate diet was lower than the low group at2-6h.The changement of glucose in portal and hepatic vein was coincidence. After ingestation, the concentration of glucose rose and at2h reached the highest value, and then descended, followed with rising at6-8h.At every determinded hour, glucose content in portal and hepatic vein in the group of high-concentrate diet was higher than the low group.The results showed that the high-concentrate diet increase absorption of propionic acid in portal vein, absorption and utilize of propionic acid in liver,and promote hepatic gluconeogenesis to enhance blood sugar level of the animal.4. Effect of diet with different concentrate roughage ratio on on levels of mRNA of key enzymes gene in hepatic gluconeogenesis in dairy goatsIn this experiment, four adult multiparous dairy goats, which were taken tissue samples of liver after trial periods to determine the levels of mRNA of PEPCK and PC gene in liver.PEPCK and PC are key enzymes in hepatic gluconeogenesis.Effect of diet with different concentrate roughage ratio on mRNA expression level of key enzymes in hepatic gluconeogenesis in dairy goats was analyzed.The results showed that high-concentrate diet could up-regulate the levels of mRNA of PEPCK and PC gene and promote hepatic gluconeogenesis.