This study was carried out to determine suitable selection factors for recipients and embryos which could improve pregnancy rates following bovine embryo transfer. The experiment included 52 surgical transfers from February, 1985 through June, 1986 performed on Kyongbuk Breeding Center in southern Korea. The pregnancy rate was highest when recipients were in estrus within 6 hours before the donor to 12 hours after the donor (78.3 % versus 50 % for recipients in estrus earlier or later). Pregnancy rates were acceptable following culture under field conditions for up to 17 hours. More recipients over 15 months of age (76.1 %) remained pregnant than those under 15 months (66.7 %). Embryos transferred during the months from February to July resulted in higher pregnancy rates than those transferred during the remaining 6 months (77.3 % versus 57.1 %). Transferrable embryos were classified A (best) to C (worst); those graded A or B resulted in significantly higher pregnancy rates than those graded C (81.8 % and 73.3 % versus 25.0 %, p0.05). Pregnancy rates among recipients of the Korean native breed tended to be higher than among Holstein recipients (100 % versus 71.1 %). Similarly, when the embryo was transferred to the right uterine horn, pregnancy rates tended to be higher than when it was transferred to the left (81.3 % versus 65 %). Pregnancy rates did not differ according to the stage of development of the embryo; they were for morulae, tight morulae, blastocysts, and advanced blastocysts, respectively : 75.0 %, 66.7 %, 75.0 %, and 77.4 %

A total of 593 mastitic pathogens was isolated from the clinical mastitic milk of dairy cattle in Kyonggi area from March 1984 to February 1988. The mastitic pathogens were further studied bacteriologically and examined for susceptibility patterns to 10 antibiotics. 173 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. The pathogens isolated from clinical mastitis were more in summer than other seasons. 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. Coliform mastitis occurred only in summer and autumn. 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

Addition of 0,01 mg/ml epibrassinolid in 100 ml laktoza-gliceryn-yolky thinner during the autumn-winter period has resulted, on the average on groups of bulls, to mobility increase sperms on 10,6 %, the survival rate sperms has increased by 17,9 %, the quantity pathological sperms has decreased on 32,5 %, safety sperm cover has increased by 4,5 %, resistance sperms has raised on 15,6 %, discoloration time blues has decreased on 8,5 %, has allowed to raise percent insemination cows and the calf on 12%