Buffering Agent Induced Lactose Content Increases via Growth Hormone-Mediated Activation of Gluconeogenesis in Lactating Goats

Abstract

AbstractDairy goats are often fed a high-concentrate (HC) diet to meet lactation demands; however, long-term concentrate feeding is unhealthy and decreases milk yield and lactose content. Therefore, we tested whether a buffering agent increases the output of glucose in the liver and influences of lactose synthesis. In this study, sixteen lactating goats were randomly assigned to two groups: one group received a HC diets (Concentrate: Forage = 6:4, HG), and the other group received the same diet with a buffering agent added (0.2% NaHCO3, 0.1% MgO, BG) as a treatment for 19-weeks experimental period. The results showed that the total volatile fatty acids and lipopolysaccharide (LPS) declined in the rumen leading to the rumen pH was stabilized in the BG group. Milk yield and lactose content increased. The alanine aminotransferase, aspartate transaminase, alkaline phosphatase, pro-inflammatory cytokines, LPS and lactate content in the plasma was significantly decreased, whereas prolactin and growth hormone levels were increased. The hepatic vein content of glucose was increased. In addition, the expression of pyruvate carboxylase (PC), phosphoenolpyruvate carboxykinase (PEPCK) and glucose-6-phosphatase (G6PC) in the liver was significantly up-regulated. In mammary gland, the glucose transporter type-1, 8, 12 and sodium-glucose cotransporter-1 levels were increased. Cumulatively, the buffering agent treatment increased blood concentrations of glucose via the gluconeogenes and promoting their synthesis in the liver. It may contribute to the increase in milk yield and lactose synthesis of lactating goats.