Effect Of Paraoxonase-1 On Risk Of Ketosis In Dairy Cow And Fatty Liver In Sheep

Fatties liver and ketosis are common metabolic diseases of ruminants in the transition period,which may affect animal production,reproductive performance and immune function,and even may be fatal due to liver failure in severe cases.It is more difficult to early monitoring and risk waring of fatty liver and subclinical ketosis in dairy cows.As the slow onset and longer duration of two diseases,it may cause great economic losses to dairy farm.Therefore,aim of this study was to measure the content and activity of PON1 and the related biochemical indexes levels in sheep fatty liver model and ketosis in an intensive farm,and to elucidate the etiologic factors and pathogenesis of fatty liver and ketosis,and then to evaluate the risk of fatty liver and ketosis in ruminants using PON1.It will provide an effective risk early warning technology for prevention of fatty liver and ketosis in ruminants in future.In this study,the lactation sheep(2-5 parities)were selected on day of calving,and fatty liver model was established by restricted feeding for 16 d.The experimental sheeps were divided into fatty liver group(n=10)and healthy control group(n=5)according to liver triglyceride content of 8 days and 16 days postpartum.T-test and Pearson correlation analysis were used to analyze the activity and content of PON1,liver fat,energy metabolism(BHBA,NEFA and GLU),blood lipid(TG,TC,HDL and LDL),liver function(TBIL,DBIL,IBIL,TP,ALB,GLB,AST,GGT,ALP,CHE and LDH)in the blood of experimental sheep,and then to predict the disease using binary regression analysis.Finally ROC analysis was used to establish the threshold and diagnostic results.Results shown that(1)Serum PON1 content and activity,LDL,TP and HDL levels in the fatty liver group were significantly lower than those in the control group at 8 days postpartum(P < 0.05).While levels of BHBA and NEFA were significantly increased(P < 0.05).At postpartum 16 days,the content and activity of serum PON1,GLU,LDL and HDL contents in fatty liver group were significantly decreased(P < 0.05).Compared with C group,and liver lipid content and the levels of serum AST,BHBA,NEFA,TG,A/G,TBIL and IBIL were significantly increased(P < 0.05).(2)There was a significant positive correlation between activity and content of PON1 in blood of sheep at 8 days postpartum in fatty liver group(R=0.581,P<0.01),a significant correlation between PON1 and liver lipid(R=-0.692),LDL(R=0.579),HDL(R=0.583),BHBA(R=-0.620)(P<0.05)for content,and then a significant correlation between PON1 and liver lipid(R=-0.862),LDL(R=-0.557),BHBA(R=-0.784),AST(R=-0.577),TP(R=0.573),GLO(R=0.573)and LDH(R=0.565)for activity(P<0.05).At 16 days postpartum,there was a significant positive correlation between activity and content of PON1 in fatty liver group(R=0.953,P<0.01),a significant positive correlation between PON1 and liver lipid(R=-0.848),NEFA(R=-0.729),GLU(R=0.653),AST(R=-0.785),GLO(R=0.587),TBIL(R=-0.602),IBIL(R=-0.608)and LDH(R=-0.623)(P<0.01)for content,and then a significant correlation between PON1 and lipid(R=-0.899),BHBA(R=-0.659),NEFA(R=-0.861),AST(R=-0.843),GLO(R=0.593),A/G(R=-0.621),TBIL(R=0.755),DBIL(R=-0.671),IBIL(R=-0.740)and LDH(R=-0.642)(P<0.05).(3)PON1,BHBA,NEFA,TG,and TP were determined to predict risk of fatty liver in sheep through regression analysis.ROC analysis was usde to obtain risk assessment threthods of PON1 activity less than 74.00 U/ml,and concentration of BHBA less than 0.97mmol/L,NEFA less than 1.29 mmol/L,TG less than 0.24 mmol/L,TP concentration less than 71.35 g/L in blood.Therefore,it suggests that activity of PON1 has the best risk warning effect on fatty liver in sheep.In this study,cows were randomly selected from 14 to 21 days postpartum as experimental animals from an intensive cattle farm in Heilongjiang.The content and activity of blood PON1,the levels of lipid,energy metabolism,liver fuction,oxidative stress and inflammation and other indicators of all the experimental cows were measured.Results shown that(1)Compared with control group,content and activity of plasma PON1 and the concentration of GLU was significantly decreased(P < 0.05),and the content of serum AST,BHBA and NEFA were significantly increased(P < 0.05)in ketosis group.(2)At 14-21 d postpartum,the activity of PON1 was significantly correlated with activity of PON1(R=0.365),BHBA(R=-0.221),AST(R=-0.297),TG(R= 0.294),SOD(R=0.298),IL-6(R=0.334)and CRP(R=0.233).Content of PON1 was significantly correlated with the BHBA(R=-0.248),GLU(R=0.292),AST(R=-0.352),ALP(R=0.231),TG(R=0.235),SOD(R=0.271),MDA(R=0.361),IL-1(R=0.412),IL-6(R=0.283),CRP(R=0.336),SAA(R=0.273),HP(R=0.382),FIB(R=0.286)and K(R=0.235).(3)By regression analysis,PON1,HDL,ALP,GLU,TG,HP and P were determined to predict the risk of ketosis in dairy cow.According to the receiver operating characteristics(ROC)analysis,early warning value of ketosis were activity of plasma PON1>71.30 U/L,content of PON1>63.43nmol/L,HDL>1.05mmol/L,ALP>51U/L,GLU>3.235 mmol/L,TG <0.195 mmol/L,HP>226.24 μg/ml and P>1.98 mmol/L.Conclution obtained that PON1 is closely related to energy metabolism,liver function,antioxidant and acute response protein.PON1,BHBA,NEFA,TG and TP may be used to assess risk of fatty liver in sheep.PON1,GLU,HDL,ALP,TG,HP and P may be used to assess risk of dairy cow ketosis.Therefore,PON1 will play an important role in predicting risk of fatty liver and ketosis in ruminants in the future.