Comparative Study of the Effectiveness of Laparotomic and Laparoscopic Methods of Transplantation of Cloned Embryos in Sheep

Abstract

Somatic cell nuclear transfer (SCNT) is considered today as the most effective method for creating genetically edited farm animals. However, the efficiency of obtaining cloned offspring remains relatively low. A number of studies on small livestock, including sheep, have shown that the use of laparoscopy, compared with the traditional method of embryo transfer via laparotomy, is associated with less trauma and allows an increase in the pregnancy rate of a recipient. Such studies have not previously been conducted with cloned embryos. The purpose of the study is to compare laparotomic and laparoscopic methods of transplanting cloned embryos in sheep. The work was carried out on Romanov breed sheep (n = 12 and 13, respectively). We preliminarily assessed the effectiveness of the ultrasound protocol used to determine pregnancy in sheep at different stages of the gestational period. Transplantation of 2-day-old cloned embryos was carried out on the 2nd day after heat detection. Diagnosis of pregnancy after embryo transfer was carried out using ultrasound on days 35–41 after transplantation. Accuracy of a positive prognosis (confirmation of pregnancy) at all periods of ultrasound diagnostics according to the applied protocol by the 28th–29th, 35th–36th, 42nd‒43rd, 56th–58th, 71st, 85th and 98th day was 100%. The use of the laparoscopic method for transferring cloned embryos was not associated with mortality during surgery, while with surgical transfer it was 8.3%. The use of the laparoscopic method made it possible to reduce the duration of the operating procedure by 2.9 times on average from 44.1 ± 13.3 to 15.4 ± 4.3 minutes (p < 0.01). The percentage of pregnancy achieved using the laparoscopic method was comparable to the results of surgical transfer of cloned embryos and was 30.8 ± 12.8% versus 36.4 ± 14.5%. In general, the use of the laparoscopic method for transplanting cloned sheep embryos is characterized by lower trauma and a significant reduction in the period of the surgical procedure without loss of effectiveness.