Bacterial infection of the uterus in Hanwoo can kill embryos. Therefore, many antibiotics have been used to treat this infection in the uterus of repeat breeders. Incorrect use of antibiotics has led to resistance in bacteria. Natural compounds have used as substitutes for antibiotics because they are safe and have very mild side effects. This study was conducted to examine the antimicrobial effects of five extracts from medicinal plants including Humulus japonicas (Hj), Phelledendron amurense (Pa), Viola mandshurica (Vm), Carthamus tinctorius (Ct), and Chelidoni herba (Ch) on bacteria isolated from the uterus of Hanwoo using the paper disc diffusion method. Hj and Pa extracts had potent antimicrobial effects against Staphylococcus lentus, Streptococcus infantarius subsp. coli, and Bacillus pumilus. Pa had the greatest antimicrobial effect among the five medicinal plants and was effective against 19 types of bacteria from bovine uterus. Compared to Pa, Hj showed weaker antimicrobial effects on all the bacteria tested except Pseudomonas aeruginosa. Vm, Ct, and Ch also showed weak antimicrobial effects on the tested bacteria. The results obtained suggest that Hj and Pa are natural compounds suitable for treating bacterial infection in repeat breeders and improving conception rates of Hanwoo.

Uterine sterilization is important for improving fertility in cattle. This study compared bacterial flora in the uterus between healthy and repeat breeder cows (RBCs). The uterine flushing of six heifers, 13 healthy HanWoo cows and eight RBCs (HanWoo) were sampled, and 15 frozen semen samples were selected. Overall, 35 bacteria were identified from in HanWoo uterine flushing and semen. The bacterial genera identified from HanWoo uterine flushing were Alloiococcus, Bacillus, Enterobacter, Enterococcus, Erysipelothrix, Gardnerella, Granulicatella, Kocuria, Pantoea, Pasteurella, Rothia, Serratia, Sphingomonas, Staphylococcus, Stenotrophomonas and Streptococcus. The bacterial genera identified from HanWoo semen were Bacillus, Escherichia, Kocuria, Oligella, Pseudomonas, Serratia, Sphingomonas, Staphylococcus, Stenotrophomonas and Streptococcus. The prevalence and presence of the identified bacteria between healthy cows and RBCs differed significantly. Further studies are needed to determine the role of these bacteria in the uterus of HanWoo cattle with reproductive disorder.