Study On The Difference Of Immunity Characteristics Of New Zealand Rabbits In SPF And Conventional Breeding Environment

In the current rabbit breeding industry,bacterial diseases caused by Gram-negative bacteria have caused great problems for rabbit breeding.Although antibiotics are a good drug treatment,there are also many shortcomings,such as drug residues and drug resistance,so improving rabbit immunity and disease resistance is a problem we must solve.Some studies have found that the environment affects the immunity of living organisms,so the immunity between the same rabbits in different breeding environments may also differ.A large number of studies have demonstrated the mechanism of influence between genetic factors and rabbit immunity,but little is known about how environmental factors affect rabbit immunity.Lipopolysaccharide(LPS)is an important component of the cell wall of Gram-negative bacteria.Injection of LPS can cause physiological and pathological processes similar to those of Gram-negative bacteria in animal organisms.TLR4 belongs to type I transmembrane receptor and is the main receptor for Gram-negative bacteria and its LPS recognition,which mediates LPS immune stress.In this experiment,24 rabbits of the New Zealand rabbits and the SPF breeding environment of New Zealand rabbits,which were continuously cultured for9 years in Qingdao Kangda Rabbit Industry,were selected as subjects to study the effects of breeding in two environments on the immune characteristics of New Zealand rabbits.The main experimental results are as follows:(1)Analysis of blood physiological and biochemical indicators of New Zealand rabbits selected under two environments,The results show:White blood cells(P<0.05),neutrophils in the blood(P<0.05),percentage of monocytes(P<0.05),red blood cells(P<0.01),mean red blood cell volume(P<0.01),and mean erythrocyte hemoglobin content(P<0.05)significantly higher than New Zealand rabbits selected under SPF environment,there were no significant differences in other physiological indicators.Biochemical indicators showed that the total protein(P<0.01),creatine kinase(P<0.01)and cholesterol(P<0.01)in New Zealand rabbitswere significantly higher than those in New Zealand rabbits selected under SPF environment.However,the content of creatinine(P<0.01)in New Zealand rabbits selected by SPF environment was significantly higher than that of New Zealand rabbits selected under normal environment.(2)Differences in body temperature and heart rate between New Zealand rabbits under two environmental conditions after LPS stimulationThere was no significant difference in body temperature between the common environment and the New Zealand rabbits selected under the SPF environment after LPS stimulation.After LPS stimulation,there was no significant difference in body temperature between New Zealand rabbits in the normal environment.The body temperature of New Zealand rabbits in SPF environment increased significantly at 3h.The body temperature is significantly reduced at 12 h.There was no significant difference in heart rate between New Zealand rabbits in the general environment and SPF environment(P>0.05),and heart rate increased significantly at 3h after stimulation(P<0.05).(3)Differences in ELISA indexes between New Zealand rabbits under two environmental conditions after LPS stimulation.This test tested 8 acquired immune indicators,including IgA/IgM/IgG,C-reactive protein(CRP),haptoglobin(HPT),major acute phase protein(MAP),lysozyme(Lys),and Natural killer cells(NK).The concentration of blood IgG in New Zealand rabbits was significantly higher than that in SPF environment after 6 hours of LPS stimulation(P<0.05).There were no significant differences among other indicators.After LPS stimulation,except for the acute phase protein,the other indicators were significantly increased,and IgA,IgM,C-reactive protein,and haptoglobin reached the highest concentration at 3 h after stimulation.(4)Differences in gene expression of TLR4 pathway in New Zealand rabbits under two environmental conditions after LPS stimulationAfter LPS stimulation,the expression levels of key node genes and downstream cytokines(TLR4,MyD88,TRAF6,NF-?B,TRIF,IRF7,IL-2,TNFa)in TLR4 pathway were significantly higher than those before stimulation,and the expression level reached the highest peak at about 3h,and then gradually decrease.The expression of TLR4 in the general environment was significantly higher than that in the SPF environment at 3h after LPSstimulation(P<0.01),indicating that New Zealand rabbits in the general environment may have higher resistance.After LPS stimulation,the expression of TRAF6 in New Zealand rabbits was significantly increased in SPF environment at 3h and 6h,and significantly higher than New Zealand rabbits in the common environment.There was no significant change in the expression of TRAF6 in New Zealand rabbits.The expression of NF-?B mRNA in New Zealand rabbits increased after LPS stimulation and was significantly higher than that in SPF environment at 3h and 6h.There was no significant change in NF-?B mRNA expression in SPF environment.In summary,there are differences in some blood physiological and biochemical indexes,ELISA indexes and TLR4 pathway gene expression levels in New Zealand rabbits under normal environment and SPF environment,indicating that the selection of different levels of environment has an impact on the immune characteristics of New Zealand rabbits.To provide a theoretical basis for studying the effects of genetic environment interactions on immune characteristics.