The Effects Of SARA On Rumen Epithelial Cell And IGF-1System In Dairy Goats

Twelve Guanzhong dairy goats were divided into four groups (n=3) randomly in this study. This study consisted of four experimental periods, fifteen days for each period. NFC/NDF ratios of diet were1.02(period I).1.24(period Ⅱ).1.63(period III).2.58(period Ⅳ) respectively. The SARA was induced by increasing dietary NFC/NDF ratio in dairy goats. Effect of butyrate and IGF-1on the development of ruminal epithelium in dairy goats were studied in vivo and in vitro, respectively.In vitro studies:The effects of SARA on rumen epithelial cell and IGF-1system expression were studied by detecting the different induction phases of DNA concentration of ruminal epithelium cell, volatile fatty acids concentration, insulin-like growth factor1(IGF-1) concentration, the expression level of IGF-1and IGF-1R in ruminal epithelium in dairy goats with increasing dietary NFC/NDF levels. The results showed that DNA concentration was increased markedly(P<0.05) with gradual increasing dietary NFC/NDF ratio.However, when NFC/NDF ratio was2.58, DNA concentration was decreased (P<0.05). The concentrations of rumen total volatile fatty acids (TVFA), propionate and butyrate were increased, of which butyrate concentration increased most significantly (P<0.01). The contents of IGF-1and IGF-1R were increased significantly with increase of dietary NFC/NDF levels, in the occurrence of SARA and higher than the contents in the induction period (P<0.05).In vivo studies: Epitheliums from caudal blind sac of goats’rumen were cultured in vitro. Cultured cells were treated with different concentration of IGF-1and butyrate sodium for24h. The cells were collected and the effects of IGF-1and butyrate sodium on the proliferation of rumen epithelial cells were studied to detect the cell cycles of them by flow cytometry. The results showed that the percentage of cells in the S-phase and G2-M phase of rumen was increased significantly (P<0.01)and the percentage of cells in the G0-G1phase was decreased after incubation with25ng/ml and50ng/ml IGF-1. That indicated IGF-1can promote the proliferation and DNA synthesis of of rumen epithelial cells.However, the percentage of rumen epithelial cells incubated with butyrate sodium was tend to decrease (P<0.01). The percentage of cells in the S-phase and G2-M phase of rumen incubated with IGF-1and butyrate sodium was tend to higher markedly than in control groups and the groups with IGF-1. The above results indicated that the increasing of dietary NFC/NDF levels can promote the synthesis of IGF-1in rumen epithelial cells and increase the content of VFA in rumen, especially increase the concentration of butyrate. Proper concentration of IGF-1and butyrate can promote the proliferation and DNA synthesis of of rumen epithelial cells.