The cycle of the seminiferous epithelia in the testis of mature Korean native cattle was divided into twelve stages, using criteria the morphological changes in the acrosomic system and the nuclei of developing spermatids and germ cells. The minimum number of type A spermatogonia were the average of 1.8 in both at stages 1 and 6, while maximum numbers were the average of 4.2 at stage 12. Some type A spermatogonia divided at stage 12 to produce the type intermediate (IN) spermatogonia at following stage 1. The intermediate type spermatogonia divided at stage 4 to produce the type B spermatogonia at stage 5

The prevalence of diarrhea caused by enterotoxigenic Escherichia coli was surveyed on 445 calves in 6 farms which were located in the central part of Korea. The incidence of enterotoxigenic Escherichia coli in calves with diarrhea was investigated by detecting the K99 and F41 antigens from the isolated strains of Escherichia coli. The incidence of colibacillosis in calves was 23.3%. Of 238 strains of Escherichia coli isolated from calves with diarrhea, 73 strains (30.6%) were proved possessing the K99 antigen by mannose-resistant hemagglutination (MRHA) using horse red blood cells and 79(33.1%) possessing F41 antigens by MRHA using guinea-pig red blood cells

The present study has been carried out to elucidate the antiestrogenic effects of tamoxifen on RNA and protein synthesis in uteri of immature rats. Immature female Sprague-Dawley rats were allocated into 4 groups and injected with 5 micro g of estradiol-17 beta, 50 micro g of tamoxifen, a combination of both, or vehicle only subcutaneously three times with an interval of 24 hrs respectively. The specific activities of 3H-uridine incorporation into uterine RNA and those of 3H-leucine incorporation into uterine protein were measured before and 1, 3, 6, 12, 24, 48 and 72 hrs after the above treatments

The purpose of this study was the examination for presence of K99 antigen (K99), enterotoxigenicity, 0-groups, colicin and antibiotic susceptibility among E. coli isolated from calves and cows. A total of 49 (18.7%) among 262 strains, isolated from 30 (26.5) out of 113 calves and cows, possesed K99, and thirty three of 49 K99+ strains produced ST. Of the strains of diarrheal calf origin which less than 15 days old, a high correlation was observed between enterotoxigenic ability and K99: 92.3% of the K99+ strains produced heat stable enterotoxin (ST)

The 587 Holstein cows which calved from Jan 1983 to Dec 1984 at an integrated dairy farm in Chungnam province were examined for the incidence of reproductive disorders and their conception rate after treatment. The incidence of reproductive disorders was 47.9% (281 heads) among 587 heads which calved. As number of calvings increased, the incidence of reproductive disorders decreased. The cows which calved in spring and summer showed significantly higher incidence of reproductive disorders than those which calved in autumn and winter (p 0.05)

The present study was undertaken to evaluate rosette formation and NK activity of splenic lymphocytes in 3-methylcholanthrene (MCA) treated mice. Mice were sensitized iv with 0.1ml of 1% sheep red blood cell (SRBC) suspension were treated with a single ip injection of olive oil alone or with different doses of MCA in oil at various time before or after sensitization, and were challenged at 4 days after SRBC. Rosette formation and NK activity of splenic lymphocytes were measured at 24 hrs after challenge

Isolation and identification of mycoplasma were performed to clarify mycoplasma infection of mice fed by convectional feeding at two (K1, K2) institutes in Korea. The twenty mice to be tested were randomly samples from each of 10 breeding colonies in respective institute. Identification of the mycoplasma strains isolated from the nasal cavity, lung and synovia of mice was made according to the morphology of colonies, biological and biochemical properties with special reference to M. pulmonis, M. arthritidis and M. neurolyticum

This paper deals with the incidence of antibiotic resistance and of R plasmids in 319 Salmonella strains isolated from various samples on 7 piggeries in Taegu, Kyongbuk, Kyongnam and Chungnam and a slaughter house in Taegu during the period from May, 1984 to May, 1985. Of the 319 strains examined, 250 (78.4%) were resistant to one or more antibiotics such as ampicillin (Am), chloramphenicol (Cm), gentamicin (Gm), kanamycin (Km), sulfadimethoxine (Su), streptomycin (Sm), rifampicin (Rf) and tetracycline (Tc), and higher resistant to Su (74.9%), Sm (53.0%) and Tc (28.5%). Only two Salmonella strains isolated from A and C farms were resistant to Rf and Gm, respectively

The measurement of angled erythrocyte sedimentation rate (ESR), as a replacement for perpendicular ESR, for cattle blood was scrutinized since it has been well known that perpendicular ESR in cattle was tpp slow to be adopted as an effective clinical test. Samples of blood were taken from 186 Korean native cattle over 2 years old. Average values of perpendicular ESR/24hrs in 15 apparently healthy cattle, as measured by Wintrobe, Westergren and capillary tubes, were 5.8 +- 2.2, 11.1 +- 3.7 and 10.4 +-4.5% respectively, which were found to be similar to the values of perpendicular ESR/hr of normal blood of human