Twin Production by Fertilized Egg Transfer in Korean Cattle

Abstract

This study investigated two blastocyst fertilized eggs of Korean native cattle (Hanwoo) developed in vitro for 3 years in 18 farm houses. The fertilized eggs were transferred into 208 cattle recipients in 7~8 days of estrous cycle. Then, their pregnancy rate, delivery rate, calf crop rate, twin crop rate and miscarriage / stillbirth rate were investigated. As a result of transferring Hanwoo blastocyst fertilized eggs developed in vitro to 208 cattle recipients, the pregnancy rate was found 53.8% (112/208); and delivery rate, 92.9% (104/112), showing no significant yearly variation. Twin delivery rate in 1st and 2nd years was 45.2% (14/31) and 47.9% (23/48), respectively, significantly higher than the 3rd-year rate of 8.0% (2/25) (P< .05). The average twin delivery rate was 37.5% (39/104). Calves produced based on pregnancy accounted for 108.1% (121/112). In the 1st year and 2nd year, the rate was 115.2% (38/33) and 114.0% (57/50), respectively, significantly higher than the 3rd year rate of 96.3% (27/26) (P< .05). The average twin calf production after Hanwoo embryo transfer was 32.2% (39/121), recording 36.8% (14/38) in the 1st year and 40.4% (23/57) in the 2nd year. In the 3rd year, 26 calves were produced including 2 twins, accounting for 7.7%. This number in 3rd year is significantly lower than the 1st and 2nd-year results (P< .05). Among the 31 calves delivered in the 1st year, 4 were stillbirths; and 4, miscarriage. The male-female cattle ratio was 10:28. Female calves accounted for 26.3%. Among the 48 calves produced in the 2nd year, 10 were miscarriage; and 4, stillbirth. A cow produced triplets. Male-female cattle ratio was 21:36. Female cattle accounted for as high as 36.8%. Among the 25 calves produced in the 3rd year, 2 were stillbirth. Male-female cattle ratio was 12:14. Female cattle accounted for 46.2%, representing good improvement result. In all of the years, the male-female ratio was 43:78. Female cattle accounted for as high as 35.5%. Miscarriage/stillbirth ratio was as high as 21.4% (24/112). The results above showed no remarkable difference in pregnancy rate and delivery rate after embryo transfer to 208 cattle recipients for 3 years. This study also found higher miscarriage/stillbirth rate than those of other studies. With respect to twin production, the 1st and 2nd-year Hanwoo embryo transfer showed significantly higher results of twin production than that in the 3rd year (P< .05). Regarding male-female ratio, female caves were found to account for larger part with time. Based on the findings, it is deemed necessary to establish improvement foundation earlier as a way to homogenize Hanwoo genetic traits and secure fattening cattle for quality meat production. Moreover, for higher income of farm houses, embryo transfer-based twin production technology will need to be developed through continued research.