Epidemiological Investigation of Diarrhea-associated Pathogens in Suckling Dairy Calf Herds in Some Areas of Ningxia
To understand the prevalence of diarrhea-associated pathogens in suckling dairy calves in the Ningxia region,334 fecal samples from suckling calves were collected from 18 large-scale dairy farms in four regions of Ningxia.The samples were tested for bovine rotavirus(BRV),bovine corona-virus,bovine viral diarrhea virus,bovine norovirus(BNoV),bovine nebovirus,bovine astrovirus,bovine torovirus,bovine kobuvirus(BKoV),bovine enterovirus,Cryptosporidium spp.,Eimeria spp.,Giardia spp.,E.coli K99,and Salmonella spp.through PCR and RT-PCR,respectively.The epidemic characteristics of pathogens and the genetic evolutionary relationship of the main epi-demic pathogens were analyzed.The results showed that a total of 13 diarrhea-related pathogens were detected in the feces of suckling calves in Ningxia,among these,cryptosporidium(38.02％),BRV(19.76％),BKoV(18.56％)and BNoV(13.77％)were the most commonly observed pathogens.The detection rates of Cryptosporidium spp.,BRV,and BKoV in the diarrhea group were signifi-cantly higher than that in the healthy group(P＜0.05).The proportion of single pathogen infection was significantly higher than that of two or more mixed pathogens(P＜0.05).The samples collected from four regions and three seasons in Ningxia had relatively higher detection rates of Cryptosporidi-um,BRV,BKoV,and BNoV.The detection rates of Cryptosporidium,BRV,and BNoV were high-er in calves aged 1 to 30 days.Meanwhile,the detection rates of Cryptosporidium and BNoV were higher in calves aged 31 to 60 days,and the detection rates of BKoV,BEV,and Cryptosporidium were higher in suckling calves above 60 days.The results of the phylogenetic analysis showed that Cryptosporidium,BRV,BKoV,and BNoV infected suckling calves were mainly Cryptosporidium parvus,BKoV type A,BKoV type B,and BNoV type GⅢ.2.The above results indicated that Cryp-tosporidium,BRV,BKoV,and BNoV are the main pathogens associated with diarrhea in suckling calves in Ningxia,and are closely related to the occurrence of diarrhea in calves.Single pathogen in-fection is the main infection type of diarrhea-related pathogens in suckling calves.The pathogenic spe-cies of calves are closely related to season and age.
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