208 EFFECT OF TWO CATTLE EMBRYO CO-CULTURE SYSTEMS ON CALVING RATE

Abstract

The objective of this study was to compare the calving rate after transfer of IVM/IVF/IVC embryos co cultured on both Vero and Vero/BRL cells (Duszewska 2000 Theriogenology 54, 1239–1247). Cumulus–oocyte complexes (COCs) were matured in TCM-199 supplemented with 10% FBS, 0.02 IU mL−1 FSH, 1 µg mL−1 17β-estradiol, 0.2 mM Na pyruvate, and 50 µg mL−1 gentamicin for 24 h at 38.5°C in 5% CO2. Spermatozoa were prepared by the swim-up procedure. COCs were fertilized in Fert-TALP supplemented with 6 mg/mL−1 fatty acid-free BSA, 0.2 mM Na pyruvate, 50 µg mL−1 gentamicin sulfate, 20 µM penicillamine, 10 µM hypotaurine, 1 µM epinephrine, and 2 µg/mL−1 heparin for 20 h at 38.5°C in 5% CO2. The zygotes were randomly allocated to one of the co-culture systems: Vero (2 × 103 cells in a 40-µL drop; 20 zygotes per drop), and Vero/BRL (1 × 103 Vero cells and 1 × 103 BRL cells in a 40-µL drop; 20 zygotes per drop). The zygotes from Vero and Vero/BRL were cultured for 168 h post-insemination in drops of Menezo B2 supplemented with 10% FBS until 144 h and from 144 h to 168 h without FBS, at 38.5°C in 5% CO2. Next, the blastocysts (Grade 1, according to IETS Manual) from Vero and Vero/BRL were transferred to recipients. The recipients were monitored daily for heat behavior, examined by ultrasound after 35 days and 65 days, and then observed monthly to confirm pregnancy. The results are presented in Table 1. Statistical significance was tested using the chi-square test. In spite of better development of cattle embryos on Vero/BRL cells than on Vero cells (P < 0.05), a lower rate of calving was obtained after transfer of these embryos to recipients than for those on Vero cells (P < 0.001). Higher loss of pregnancy after transfer of Vero/BRL embryos was observed in Days 35–65, which may indicate early fetal resorption. All calves were born naturally, healthy, and with normal weight. Table 1.Calving rate after transfer of embryos co-cultured on Vero cells and on Vero/BRL cells This work was supported by KBN Grant 2P06D05228.