Identification of pathogenic microorganisms of repeat breeder dairy cows and a hyperimmune treatment approach

Objective:To investigate the bacterial infections in repeat breeder dairy cows and to evaluate the treatment effects of hyperimmune serum against two main endometritis bacteria,Escherichia(E.)coli and Trueperella pyogenes.Methods:A total of 29 Holstein multiparous cows with three or more unsuccessful artificial inseminations were carried out and examined to confirm the absence of reproductive tract abnormality and vaginal discharges.Uterine lavage was performed to collect uterine samples for bacterial and fungal cultures.In addition,polymerase chain reaction(PCR)was done to detect Trueperella pyogenes,E.coli,Fusobacterium necrophorum,and Prevotella melaninogenicus.The cytological study was done on cervical mucus.The hyperimmune serums produced against Trueperella pyogenes and E.coli were infused into the uterus of repeat breeder cows and two doses of prostaglandin F2αwere administrated intramuscularly within 14 days'interval.Results:There were 10 positive samples in the bacterial culture with 19 isolations and no growth of the main causative bacteria of endometritis.In the PCR method,no Trueperella pyogenes,Fusobacterium necrophorum,and Prevotella melaninogenicus were found.However,11 positive samples of E.coli were identified by PCR.Cladosporium was detected in one case of repeat breeder cows.The median(interquartile range)of neutrophils in vaginal discharge was 12(22.5).Eighteen from twenty-nine(62.1%)repeat breeder and eight from eleven(72%)cows with E.coli infections in PCR were made pregnant in the first artificial insemination after treatment by intrauterine infusion of hyperimmune serum and prostaglandin F2α.Conclusions:Intrauterine administration of hyperimmune serum could be an alternative to antibiotics for the treatment of repeat breeder cows.