• Journal of Veterinary Clinics
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• v.36 no.4
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• pp.185-189
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• 2019

Respiratory pathogens of calves including bovine parainfluenza type 3 virus (BPI3V), bovine respiratory syncytial virus (BRSV), infectious bovine rhinotracheitis virus (IBRV) and Mycoplasma spp is well-known for winter pathogens. However, there are no studies about summer pneumonia pathogens of calves in Korea. The aim of this study was to detect respiratory pathogens from calves with summer pneumonia. Eighty calves from 5 regions were chosen and their nasal swabs were used to detect respiratory pathogens with real-time PCR. Mycoplasma spp was major primary respiratory pathogens in calves with summer pneumonia. Although, the detection rates of respiratory viruses were very low, serological assays showed that respiratory viruses exist widely in farms.

• 한국생물공학회:학술대회논문집
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• 2003.10a
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• pp.740-744
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• 2003

The antimicrobial substance produced by Lactobacillus bulgaricus was inactivated by pretense, which confirmed it as a bacteriocin and referred to 'bulgaricin HJ'. The bulgaricin HJ showed the inhibitory activity against mastitis pathogens, gram-positive and gram-negative bacteria. The optimal conditions for the production of bulgaricin HJ were at the temperature of $30^{\circ}C$ and 10 h after cultivation of L. bulgaricus. Staph. and Strep. agalactiae, common bovine mastitis pathogens, were treated with bulgaricin HJ by the agar well diffusion method and showed antimirobial activities to the bovine mastitis pathogens. The activity of the bulgaricin HJ was maintained at pH 6-7 and $100^{\circ}C$ for 60 min against the mastitis pathogens. The bulgaricin HJ was determined as class IV bacteriocin by various enzyme treatments. Colony forming units analysis with indicator strains by the treatments of bulgaricin HJ indicates that the mode of bacteriocin action was bactericidal rather than bacteriostatic.

• The Korean Journal of Food And Nutrition
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• v.12 no.1
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• pp.7-12
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• 1999

Bovine mastitis was examined by use of the rolling ball viscosity test in Kwang-ju area. Antibiotic sus-ceptibility of isolated pathogens from raw milk was investigated by the disc method. Positive rate of so-matic cell counts (over 500,000 cells/ml) was decreased from 11.1% in 1991∼1993 to 8.0-% in 1995∼1997. Isolated mastitis-causing-pathogens were identified as Staphylococcus sp. (49.7%) Escherichia coki(23.2%) Streptococcus sp. (10.4%) and Bacillus sp(7.2%) Antibiotic susceptibility of isolated pathogens to almost antibiotics was decreased.

• Korean Journal of Veterinary Service
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• v.15 no.2
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• pp.150-165
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• 1992

The study for a effect of monitoring on bovine mastitis was conduced for a year from Dec, 1989 to Nov, 1990, Sampling the bulk milk of 350 herds in Inchon city and out of 10 herds among them were carried out herds guidance, CMT, SCC, isolation of pathogens and antibiotic sensitivity tests. The results obtained were summarized as follows 1. Annual mean SCC of 1213 herds was 558, 000 cell /ml 2. The number of SCC below 500, 000 cell /ml to quarters for herds guidance was at 1st 77. 0%, End 84.8% and 3rd 80.4%. The is shown that milk quality was steadly improved. 3. The most number of isolated pathogens of bovine mastitis was Staphylococcus SPP - 402(47.2%) Streptococcus SPP - 80(18.7% ) 4. The highest rate of antibiotic sensitivity test was Stapylococcus SPP - cephalothin(76.7%) Streptococcus SPP - ampicillin(77.5%) Gram negative bacilli - tetracyclin(76.0%) 5. The effect of monitoring on bovine mastitis was improved showing that at 1st 49.0% to 3rd 72.0%

• Korean Journal of Veterinary Service
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• v.46 no.2
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• pp.147-156
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• 2023

Between February 2020 and September 2021, a total of 452 dairy calves with diarrhea were investigated across 17 dairy farms in Gyeonggi province, Korea, using a rapid diagnostic kit. The study aimed to examine the infection rates of major pathogens causing diarrhea in dairy calves, categorizing them by season, age, and birth month. Additionally, logistic regression analysis was conducted to investigate the factors affecting the infection rate. The infection rates of the major pathogens causing infectious diarrhea in dairy calves, including bovine rotavirus, bovine coronavirus, Cryptosporidium, and E. coli, are influenced by season, age, and birth month. Bovine coronavirus and Cryptosporidium showed variations in infection rates according to season, age, and birth month, while bovine coronavirus was influenced by age and birth month, and E. coli showed variations in infection rates based on age. Furthermore, in the analysis of risk factors influencing the infection rates of these pathogens, age and birth month were identified as risk factors for bovine rotavirus, bovine coronavirus, and Cryptosporidium.

• Journal of Animal Science and Technology
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• v.63 no.4
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• pp.864-871
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• 2021

Infectious calf diarrhea is one of the most significant diseases of neonatal calves. This study is conducted to identify the prevalence of pathogens in calf diarrhea for 2 years. A total of 544 feces samples from Korean native beef calves were obtained to investigate selected seven pathogens causing calf diarrhea: bovine rotavirus, bovine coronavirus, Cryptosporidium parvum, bovine viral diarrhea virus, Eimeria species, Escherichia coli K99, and Salmonella species. The presence of diarrhea, the number and species of detected pathogens, and the calves' ages were analyzed using various statistical methods depending on the case. Of the 544 calves, 340 calves (62.5%) had normal feces and 204 calves (37.5%) had diarrhea. The presence of pathogens was significantly associated with diarrhea (p < 0.01) and fecal scores and the number of detected pathogens showed a significant linear trend (p < 0.001). Of the 7 target pathogens, 6 were detected in samples, but only C. parvum (p = 0.001) and bovine rotavirus (p < 0.001) were found at significantly higher rates in diarrheic calves than in non-diarrheic calves. Only Eimeria spp. showed a significant linear trend between the detection rate of the pathogen and the age groups (p < 0.05).

• Journal of Veterinary Clinics
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• v.23 no.3
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• pp.286-290
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• 2006

To find alternative agents for bovine mastitis, the extracts of 30 selected herbal medicine were screened for their antibacterial activity against mastitis pathogens. The extracts of 9 herbal medicine, Terminaliae chebula, Cinnamonum loureirii, Paeonia japonica, Inula britannica, Caesalpinia sappan(C. sappan), Salix babylonica, Alpinia katsumadai, Polygonum aviculare and Coptidis japonica showed strong antibacterial activity. Among of them, C. sappan extract was found to be the most active against all bacteria in this experiment. Methanol extract of C. sappan and brazilin, the main component of C. sappan, had inhibitory activity against a variety of pathogens, however they had less of an inhibitory effect on gram negative bacteria. Minimal inhibitory concentrations of brazilin against gram positive pathogens was lower than that of methanol extract. These results showed that the extract of C. sappan has a potential as a therapeutic agent for bovine mastitis.

• Korean Journal of Veterinary Service
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• v.42 no.2
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• pp.93-112
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• 2019

Calf diarrhea is a common disease in young claves and is still a major cause of productivity and economic loss in livestock farms. Fecal samples from Korean native cattle (n=100) with diarrhea from 64 farms in Gwangju area, Korea from september 2017 to December 2018 were examined for shedding of important protozoan parasitic, viral and bacterial pathogens using culture, rapid test kit and PCR methods. Of 57 (89.1%) of the 64 Korean native cattle farms examined had samples infected with at least one of the investigated pathogens. Among 100 fecal samples, 88 samples were positive for at least one the twelve pathogens and 51 samples were simultaneously positive for two or more pathogens by culture and PCR assay. Bovine group A rotavirus (BRV) was the most common pathogen, found in 43/100 (43.0%) samples on 32/64 (50.0%) farms. Subsequently, kobuvirus (30.0%), pathogenic E. coli (29.0%), bovine parvovirus (17.0%), Giardia spp. (13.0%), Eimeria spp. (10.0%), Clostridium perfringens type A (8.0%), bovine torovirus (8.0%), bovine viral diarrhea virus (6.0%), bovine coronavirus (5.0%), bovine norovirus (2.0%) and Cryptosporidium spp. (2.0%) were detected. Nebovirus, kırklareli virus, bovine adenovirus, Salmonella spp. and intestinal parasites were not detected. Of the 72 calves sampled in this age group, 64 (88.9%) samples were positive for at least one enteropathogen. BRV was identified in 34/72 (47.2%) samples from 27/48 (56.3%) farms. Subsequently, pathogenic E. coli (30.6%), kobuvirus (29.2%), BPaV (22.2%), Giardia spp. (15.3%), Eimeria spp. (9.7%), BVDV (6.9%), Cl. perfringens type A (6.9%), BCoV (4.6%) and Cryptosporidium spp. (2.8%) were detected in fecal samples. A total of ninety-six strains of E. coli were isolated from one hundred fecal samples collected from Korean native cattle with diarrhea. The presence of stx1, stx2, eaeA, LT, STa, STb, ehxA, saa, F4, F5(K99), F6, F17, F18 and F41 genes in the isolates was investigated by PCR. Out of ninety-six E. coli isolates screened for specific genes, 30 strains E. coli were identified to harbor shiga toxin-producing E. coli (STEC) 7 (7.3%), enterohemorrhagic E. coli (EHEC) 8 (8.3%), enteropathogenic E. coli (EPEC) 6 (6.3%), enterotoxigenic E. coli (ETEC) 2 (2.1%) and STEC/ETEC hybrid 7 (7.3%). This study provides epidemiological estimates of the prevalence of Korean native cattle's enteropathogens in Gwangju area, Korea, which would be used for cattle farmers and veterinarians to select appropriate therapeutic method.

• Korean Journal of Veterinary Research
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• v.28 no.2
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• pp.397-404
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• 1988

A total of 593 mastitic pathogens were isolated from the clinical mastitic milk of dairy cattle in Gyeonggi area from March 1984 to February 1988. The mastitic pathogens were further studied bacteriologically and examined for susceptibility patterns to 10 antibiotics. The results obtained were summerized as follows: 1. One hundred and seventy three pathogens were isolated in the first year of studies, 205 pathogens in the second year, 122 pathogens in the third year and 93 pathogens in the last year. 2. The pathogens isolated from clinical mastitis were more in summer than other seasons. 3. Staphylococcus spp (50%) and Streptococcus spp (18%) were the main pathogens in the first year of studies but coliforms (15%) and other bacteria (40%) were the main pathogens in the last year of studies. 4. Coliform mastitis was occurred only in summer and autumn. 5. Antibiotic susceptibility patterns of the same genuses from clinical mastitis infections in different herds and in different years varied greatly. Therefore, treatment should be selected on the basis of susceptibility test results.

• Journal of Veterinary Clinics
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• v.3 no.1
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• pp.277-298
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• 1986

This paper reviews the mechanisms effecting host defense in the mammary gland and assesses their possible in preventing of bovine mastitis. The streak canal is the first line of defense against invading mastitis pathogens, providing a physical barrier and antibacterial substances. The milk leukocytes are a second defense line by ingesting pathogens breached the streak canal by multiplication, physical passage, and propulsion during milking. Leukocytosis in milk and enhancement of the phagocytic defense machanisms of the udder were accomplished by inserting intramammary devices. Milk antibodies serum derived and synthesized in mamma tissue aggregate and opsonise bacteria, agglutinate and neutralise toxins, and inhibit. binding of bacteria to epitherial surfaces. Vaccination generally has been unsuccessful because protection is not absolute, but immunization is useful in controlling specific pathogens. Immunostimulant to enhance locally the protective nature of antibody-producing plasma cells concentrated in internal teat end tissue may be effective in reducing the occurrence of infection, but ineffective in preventing intramammary infections.