The Effect Of Acute Cold Exposure On Metabolism And Some Immune Indexes In Blood Of Weaned Piglets

Cold stress is one of the most common environmental and climatic adversity factors that animal husbandry faces in cold areas of China,which seriously affects the healthy development of livestock and poultry.The purpose of this study was to investigate the effects of acute cold exposure on metabolism and immune indexes in blood of 30-day-old weaned piglets.16 weaned piglets were randomly divided into normal temperature(NT)group,cold exposure 2 h(CE2h)group,cold exposure 6 h(CE6h)group and cold exposure 12 h(CE12h)group.The feeding temperature of NT group was 24±2 ?,and that of CE group was 4±2 ?.In order to evaluate the stress state of weaned piglets,the changes of arterial blood electrolyte,blood gas parameters and serum cortisol(CORT)levels were measured.The results showed that there was no significant change in arterial p H(P>0.05),The levels of partial pressure of carbon dioxide(PCO2),total carbon dioxide(t CO2),and bicarbonate ion(HCO3-)in weaned piglets after cold exposure showed a trend of first declining and then recovering.In CE6 h group,the levels of t CO2(P<0.05),HCO3-(P<0.01)were significantly lower than that of NT group.The levels of Na+,K+,Cl-,and Angap showed a trend of first rising and then recovering.The levels of Na+(P<0.05),K+(P<0.01),Cl-(P<0.05)and Angap(P<0.001)in CE6 h group were Significantly higher than that of NT group.The serum CORT level showed a trend of rising first and then recovering,which was significantly higher in CE6 h group than that in NT group(P<0.01).These results indicated that 6 hours of cold exposure induced acid-base imbalance and serum CORT levels elevate in weaned piglets,and the acute cold exposure model of weaned piglets was successfully constructed.In order to explore the effect of acute cold exposure on the blood metabolic indexes of weaned piglets,the levels of blood glucose(Glu),total protein(TB),albumin(ALB),globulin(GLO),blood urea nitrogen(BUN),creatinine(Cr),creatine kinase(CK),calcium(Ca),inorganic phosphorus(P),total bilirubin(TBil),triglyceride(TG),aspartate aminotransferase(AST),alanine aminotransferase(ALT),amylase(AMY),arachidonic acid(AA)and glutamine(GLN)in blood of weaned piglets were detected by biochemical analysis and ELISA Kinase.The results showed that Glu,Cr,CK levels after cold exposure showed a trend of first declining and then recovering.The levels of Cr(P<0.05),CK(P<0.01)in CE6 h group were significantly lower than that in NT group.The levels of TB,ALB,GLO,P,TBil,TG,AA and GLN showed a trend of first rising and then recovering.The levels of TB(P<0.001),ALB(P<0.01),GLO(P<0.01),P(P<0.001),Tbil(P<0.05),TG(P<0.01),AA(P<0.01),and GLN(P<0.05)in CE6 h group were significantly higher than that in NT group.There were no significant changes in the levels of BUN,Ca,AST,ALT and AMY(P>0.05).These results indicated that acute cold exposure can cause significant changes of Glu,TB,ALB,GLO,Cr,P,TBil,TG,CK,AA and GLN levels in serum of weaned piglets.In order to investigate the effect of acute cold exposure on some immune indexes of weaned piglets,the levels of immunoglobulin,inflammatory cytokines and stress protein HSP70 were detected by ELISA and q RT-PCR.The results showed that there was no significant change in the levels of Ig G and Ig M(P>0.05).The levels of TNF-? and IL-6 m RNA showed a trend of first rising and then recovering.The levels of TNF-? and IL-6 m RNA in CE6 h group were significantly higher than that in NT group(P<0.001).And the level of IL-10 m RNA showed a trend of first declining and then recovering.The level of IL-10 m RNA in CE6 h group were significantly lower than that in NT group(P<0.001).The level of HSP70 m RNA in CE2 h and CE6 h group was significantly higher than that in NT group(P<0.001).The results showed that acute cold exposure could change the levels of TNF-?,IL-6,IL-10 and HSP70 m RNA in the whole blood of weaned piglets.Conclusions: The acute cold exposure model of weaned piglets was successfully constructed.Acute cold exposure can change the levels of Glu,TB,ALB,GLO,TBil,Cr,CK,TG,P,AA and GLN in the serum of weaned piglets,and cause the expressions of inflammatory cytokines TNF-?,IL-6,IL-10 and stress protein HSP70 m RNA changed significantly.So that the body had a variety of adjustments in glucose metabolism,lipid metabolism,protein metabolism,amino acid metabolism and energy homeostasis,as well as activated innate immunity to maintain the homeostasis.