This paper deals with the distribution of Salmonella (S) infection on 4 herds in Kyungju and Taegu during the period from May to October 1986. Isolated Salmonella were examined for serotypes, antimicrobial drug resistance and detection of R plasmid. From 4 herds, 67 Salmonella were isolated from 51 samples (1.1%), and their serovar strains were S. typhimurium 6, S. derby 5, S. infantis 4, S. bareilly 4, S. dublin 3, S. anatum 2, S. montevideo 2 and untypable 41. In 4 herds, the incidence of drug resistance was 57.7-100% and transfer frequency of conjugative R plasmid was 96.1-100%.

Environmental mastitis has increased particularly in well-managed or low somatic cell count herds that have successfully controlled contagious pathogens. Major pathogens of environmental mastitis are Escherichia coli (E. coli) and Streptococcus uberis. The present study was conducted to investigate the isolation and antibiotic susceptibility of 406 (21.8%) gram-negative bacteria isolated mastitis milk from 1,865 quaters of 241 Korean dairy farms from 2001 to 2004. Prevalence of major gram-negative bacteria isolated from mastitis milk were E. coli (22.7%) and Enterobacter spp. (16.3%) in coliforms and Pseudomoas spp. (10.3%) and Serratia spp. (7.9%) in non-coliforms.

To determine the effects of β-carotene on the control of mastitis in dairy cows during the dry period, 38 dairy cows (18 mastitic cows and 20 healthy cows) were administered with 5ml of β-carotene (30 mg/ml) intramuscularly twice (4 week intervals). Blood samples were taken from the cows before the injection and two weeks after the second injection, respectively, and were measured for the cows before the lymphocyte subpopulations and lymphocyte proliferation responses.

Streptococcus spp. comprising Streptococcus (S.) uberis and S. dysgalactiae strains is major cause of bovine mastitis from particularly well-managed or low somatic cell count herds that have successfully controlled contagious pathogens. In this study, antimicrobial susceptibility and genetic characteristics of S. uberis isolated from clinical or subclinical mastitis milk at 2003 were investigated. Eighty seven isolates of Streptococcus spp. were identified by the conventional biochemical methods. The antimicrobial susceptibility by disk diffusion method was determined for 46 S. uberis, 11 S. bovis, 10 S. oralis, 6 S. uberis and 14 other Streptococcus spp., Overall, the tested strains were susceptible to tetracycline (11.5%), amikacin (14.9%), streptomycin (16.1%), neomycin (26.4%), kanamycin (35.6%), gentamicin (65.2%), oxacillin (70.1%), ampicillin (75.9%), chloramphenicol (78.2%), and cephalothin (97.7%).

This study was conducted to analyze the relationship between the occurrence of mastitis and the conformation of udders, teats, and teat tips of Holstein cows raised in Korea. Udders, teats, and teat tips were categorized by their conformation and the teat length, teat diameter and the distance from the tip of teat to the ground of 259 cows were measured. The most common shapes of udder, teats and teat tip were milking machine udder (27.4%), U-shaped teats (53.9%) and disk teat tip (53.8%), respectively.