The Screening Of Diagnosis Indexes Of Fatty Liver In Dairy Cows And The Effects Of Oxidative Stress On The Activity Of Oct Of Mitochondrial In Calf Liver

Fatty liver was one of the nutritional and metabolic diseases in dairy cows. It was caused to the block of lipid metabolism and the accumulation of excessive lipid as the form of triglyceride in cow liver, accompanied by severe liver dysfunction. Fatty liver often happens during the perinatal period, in which the metabolism and physiology condition change greatly. The incidence of fatty liver was over 50% in cow, cows with fatty liver present obvious decline of milk production and decrease of fecundity and immunity, which seriously hinders the development of dairy industry. Thus to diagnose the fatty liver of cow in time was very impotant. Presently, the diagnosis of fatty liver was only based on liver biopsy. However its operability and feasibility was poor due to the high demands of this method to operators’ ability and the influnce on inspected dairy cows’ production ability in the production practice. In order to diagnose the fatty liver of dairy cow more conveniently and correctly, this article explored the clinical diagnosis methods and potential diagnostic indexes of the fatty liver of cow. Another study reported that high fat diet will lead to mitochondrial oxidative stress in the liver of dairy cattle, and the level of ornithine carbamoyl transfer transferase(OCT), liver mitochondrial specific enzyme, in bovine serum of fatty liver was elevated. But the relationship between mitochondrial oxidative stress and mitochondrial OCT activity remained unclear. In this study, calf liver mitochondria isolated in vitro as a model of oxidative damage to explore the effect of oxidative stress on OCT activity in calf liver mitochondria. The results are as follows:1. Plasma biochemical indexes of the 112 tested cows, including aspartate aminotransferase(AST), total bilirubin(TBIL), triglyceride(TG), calcium(Ca), potassium(K+), non-esterified fatty acids(NEFA), OCT, lipopolysaccharide(LPS) were analysed by two kinds of mathematical statistics analysis method, including principal component analysis and cluster analysis. And ultrasonic inspection and body condition score were auxiliary means. All these methods explored the potential clinical comprehensive diagnosis indexes in cows with fatty liver. The results of biochemical indicators test indicated that the 112 cows of the seizure can be divided into three groups. Cows with suspected fatty liver are 13, in which postpartum cows accounted for 84%; while healthy cows are 7; cows in potential disease group are 92. The incidence of fatty liver cows of perinatal accounted for 44% of perinatal cows. The levels of NEFA, LPS, OCT, TBIL, K+ and AST were increased, but the levels of Ca and TG were decreased. 10 heads of cows of suspected fatty liver group with ultrasound examination can found liver liquid and suspected calcification of the bright spot, which was suspected to fatty liver. The body condition score of the suspected fatty liver group was 4.25 and the score was high.2. In order to investigate the effect of calf liver mitochondrial oxidative damage on OCT activity, the Fenton reaction of Fe2+/H2O2 system was used to construct calf liver mitochondria oxidative damage model in vitro, and detect the activity of OCT. The results showed that with the increase of H2O2 concentration, the contents of mitochondrial malondialdehyde(MDA) and the degree of swelling were increased, the activity of succinate dehydrogenase(SDH) and OCT were decreased in mitochondria, and represented the concentration dependent relationship in a certain range. The free radical scavenger mannitol can inhibit the lipid peroxidation and swelling of mitochondria and the decrease of SDH activity of mitochondria induced by Fenton reaction. Under conditions of Fenton reaction, mitochondria oxidative damage model of the separated calf liver in vitro was successfully build. The OCT activity in mitochondria was decreased significantly in high concentration of Fe2+/H2O2 reaction system.Conclusions are bellow derived from results above:1. The plasma biochemical parameters NEFA, OCT and TBIL can be used as the clinical diagnosis indexes of fatty liver of dairy cow, and LPS can also be used as the reference index of fatty liver in dairy cows. The ultrasound examination and body condition score can be used as the clinical assistant diagnostic tool for the fatty liver of dairy cow.2. Calf liver mitochondria damage model is successfully constructed in vitro by using Fenton reaction system. The activity of OCT in mitochondria can be affected by the degree of mitochondria oxidative damage. One of the possible mechanisms of the increased activity of OCT in serum of cows fatty liver is mitochondria oxidative stress formated.