EMBRYO TRANSFER PROGRAM IN PARAGUAY BY USING OPU-DERIVED COCS EMBRYOS: EMBRYONIC AND FETAL MORTALITY RATES

ARRESEIGOR C; KONRAD J.L.; ARZA-SPINZI F; BANDEO A.; DRIEDGER B; BERDUGO J. A.; GUTIÉRREZ-REINOSO M; GARCÍAHERREROS M; SANSIÑENA M; MALDONADO VARGAS P.

Bologna

Congreso; 19th International Congress on Animal Reproduction BOLOGNA (ITALY); 2022

BACKGROUND-AIMIn vitro embryo production (IVP) is a feasiblebiotechnological tool that can be used in domesticanimal species of economic interest, being an interestingalternative for the acceleration of animal reproductiveprocess and the genetic improvement. Despite theconsiderable development of IVP techniques, its efficiencystill remains low compared to other biotechnologies, in partdue to the high rates of embryonic and fetal losses. Theobjective of this study was to assess the loss outcomes ofa commercial embryo transfer program in several bovinebreeds.METHODSCumulus-Oocyte-Complexes (COCs) were obtained byovum-pick up (OPU) from Bos indicus (Nelore, n=1,569;Gyr, n=1,086), Bos taurus (Holstein, n=401; AberdeenAngus, n=1,276) and Bos taurus x Bos indicus (Brangus,n=182; Girolando, n=297) cattle and transported to thelab located in Asunción (Paraguay). The IVP protocolused was the same for all breeds. Embryos were culturedfor 7 days post-fertilization and transferred to synchronizedrecipients (developmental stages 4 to 7, IETS) 9 days afterCIDR removal. Pregnancy rates (PR; %) were scored byultrasonography 23 days post-transfer (Day 30, 45 and60) to determine embryonic (EMR; %) and fetal mortality(FMR; %) rates. The comparative analysis was performedby ANOVA.RESULTSThe PR was 33.9±9.6 (19,195 transfers/6,503 pregnancies).The EMR at Day 45 was 5.2±7.1 (343 pregnancies) and theFMR at Day 60 was 1.6±2.8 (105 pregnancies). There wasno effect of breed on PR (p=0.473). Significant differenceswere observed in EMR (p=0.008), being higher in theHolstein breed (18/147, 12.2±1.9). No significant differenceswere observed in pregnancy losses at Day 60 irrespectiveof the breed (p>0.05). The PR in 4th to 7th stage transferredembryos was 33.4, 30.5, 37.2, and 40.6%, respectively,being higher in 6th and 7th stage blastocysts compared toany other developmental stage (p