The Effect Of Different Energy Intake During The Dry Period On Glyconeogenesis In The Periparturient Cows

Thirty healthy periparturient Chinese-Holstein dairy cows were randomly allocated into three groups to study the effect and the regulatory mechanism of different energy intake during the dry period on glyconeogenesis. The cows were fed with 100% energy diet, 120% energy diet and 80% energy diet, respectively, beginning at the day 28 prior to parturition. After calving, all the cows were offered the lactation ration ad libitum up to the day 56 postpartum. The levels of some metabolites and hormones in the peripheral blood and of insulin receptor(IR) mRNA, pyruvate carboxylase (PC) mRNA and phosphoenolpyruvate carboxykinase (PEPCK) mRNA abundance in the liver were measured by radioimmunoassay, quantitative reverse transcription polymerase chain reaction(RT-PCR)and automatic biochemistry analyzer. The results showed as follows:1.The cows fed with high energy diet during the dry period reduced 6% of the dry matter intake (DMI) and 21% of milk yields (MY). It increased the loss in body weight and aggravated the negative energy balance, while the cow fed with low energy diet during the dry period increased 6% of the DMI and 6% of MY. It had a less loss in body weight after parturition, thus not only relieve the negative energy balance but also shorten the duration.2.The cows fed with low energy diet during the dry period had the highest level of blood glucose compared with the other two groups of cows,however,there was no significant difference among the groups.3.The cows fed with low energy diet during the dry period had the highest abundance of PC mRNA and PEPCK mRNA in liver compared with the other two groups of cows and there was significant difference among the groups.4.The cows fed with low energy diet during the dry period, had an increasing plasma concentrations of glucagons, reducing plasma concentration of insulin and increasing GN/INS and improved the liver glyconeogenesis. While the cows fed with high energy diet during the dry period had opposite results.5.The concentration of insulin in hepatocyte culture of calf showed inverse correlation with the abundance of insulin receptor(IR). The abundance of IR mRNA in the cows fed with low...