| Endotoxin is a toxic substance released when Gram-negative bacteria grow or die.Due to its high heat resistance,it pollutes the living environment of livestock and poultry and exists in large quantities.Coupled with the abuse of antibiotics in the breeding process of livestock and poultry farms,a large number of endotoxins are released from dead bacteria and translocated into the blood,causing a series of serious complications such as endotoxemia.Gram-negative bacteria are currently one of the most important bacteria in the reproductive tract infection of cattle,sheep,pigs and poultry in the breeding industry.Endotoxins are extremely harmful to the reproduction and immunity of livestock and poultry,which can lead to diseases such as weak diarrhea in piglets born to sows,self-malnutrition,infertility,abnormal lactation,early or late embryonic death or autolysis and endometritis in sows.However,the mechanism by which endotoxin in pigs affects the reproductive and growth performance of pig farms is still unclear.Therefore,this study collected blood from healthy pigs at different physiological stages in three large-scale sow farms to analyze the changes in the levels of endotoxin and inflammatory factors in the blood;assessing the correlation of endotoxins with reproductive and growth performance and reproductive hormones of sow farms in different pig farm environments.In order to further verify that endotoxin is a key factor affecting the reproductive performance of pigs,a regression model of LPS-infected pregnant mice was established to find out the effect of endotoxin on the reproductive and growth performance of female mice,and to detect the mRNA expression of key factors in the TLR4/MyD88/NF-KB signaling pathway,in order to elucidate the pathogenesis of the effect of endotoxin on the reproductive performance of livestock.The results of this test are as follows:1.The blood endotoxin levels of pigs in each physiological stage of pig farm-I and pig farm-II were significantly lower than those of pig farm-III(P<0.05).The most important finding was that the blood endotoxin levels in the gilts of the three pig farms were the highest,the endotoxin levels in the multiparous sows decreased with the increase of parity,the content of endotoxin in umbilical cord blood of piglets increased with the increase of endotoxin content in sow.The above test shows that endotoxin is more harmful to sows and piglets.2.In order to further study the effect of endotoxin on sows and piglets,we analyzed the correlation between endotoxin and reproductive performance of sows in three pig farms.The results showed that the reproductive performance such as litter-average healthy piglets,delivery rate and the levels of reproductive hormones such as FSH and LH of sows in pig farm-III were significantly lower than those in pig farm-I and pig farm-II(P<0.05).There was a negative correlation between the endotoxin of pig farm-III and the number of piglets born alive in different parities of sows,but there was no correlation between the endotoxin of pig farm-I and each reproductive performance indicator.The endotoxin of pig farm-III was negatively correlated with the levels of FSH,LH,P4,but had no correlation with E2,while endotoxin of pig farm-I had no correlation with each reproductive hormone.The endotoxin of pig farm-III was negatively correlated with the gilt 7-day mating rate and the 7-day mating rate after weaning.The above experiments showed that endotoxin was significantly negatively correlated with the reproductive performance of sows.3.To further determine the negative effects of endotoxin on reproductive performance of sows,we established a model of endotoxin-infected pregnant mice.The results showed that the pregnancy rate and the survival rate of pups in the exposure group were significantly lower than those in the control group,and endotoxin was negatively correlated with the number of live pups born in the female mice.On the 15th day after delivery,the contents of LPS in the colon,ileum and uterus of the control group were significantly higher than those in the exposure group(P<0.05),while the content of LPS in the intestinal tract of the offspring was significantly lower than that in the exposed group(P<0.05).The intestinal sIgA level of the offspring mice in the exposure group decreased significantly,which made the offspring mice appear immunosuppressed.The expression of TLR4,MyD88 and NF-κB factor mRNA in the intestinal and uterine tissues of the exposure group was significantly higher than that of the control group(P<0.05).The above experiments show that LPS can further affect the reproductive performance of female mice by regulating the levels of inflammatory factors in the TLR4/MyD88/NF-KB signaling pathway,but the specific related mechanism remains to be further studied.In conclusion,by monitoring blood endotoxin levels of pigs at various physiological stages of three large-scale pig farms and endotoxin-infected pregnant mice,it was found that endotoxin was significantly negatively correlated with the conception rate of dams and the survival rate of pups,LPS affects the reproductive performance of female animals by mediating key factors in the TLR4/MyD88/NF-κB signaling pathway.The above test results provide a scientific basis and theoretical basis for the effect of endotoxin on the reproductive performance disorder of female animals in breeding farms in the future. |
