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 GUTIERREZ, J.; GUTIÉRREZ REINOSO, M.A.; GARCÍA HERREROS, M.; SANSINENA, M.; MALDONADO VARGAS, P.

Bologna

Congreso; 19th International Congress on Animal Reproduction; 2022

ICAR

In vitro embryo production (IVP) is a feasible biotechnological tool that can be used in domestic animal species of economic interest, being an interesting alternative for the acceleration of animal reproductive process and the genetic improvement. Despite the considerable development of IVP techniques, its efficiency still remains low compared to other biotechnologies, in part due to the high rates of embryonic and fetal losses. The objective of this study was to assess the loss outcomes of a commercial embryo transfer program in several bovine breeds. Cumulus-Oocyte-Complexes (COCs) were obtained by ovum-pick up (OPU) from Bos indicus (Nelore, n=1,569; Gyr, n=1,086), Bos taurus (Holstein, n=401; Aberdeen Angus, n=1,276) and Bos taurus x Bos indicus (Brangus, n=182; Girolando, n=297) cattle and transported to the lab located in Asunción (Paraguay). The IVP protocol used was the same for all breeds. Embryos were cultured for 7 days post-fertilization and transferred to synchronized recipients (developmental stages 4 to 7, IETS) 9 days after CIDR removal. Pregnancy rates (PR; %) were scored by ultrasonography 23 days post-transfer (Day 30, 45 and 60) to determine embryonic (EMR; %) and fetal mortality (FMR; %) rates. The comparative analysis was performed by ANOVA. The 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 the FMR at Day 60 was 1.6±2.8 (105 pregnancies). There was no effect of breed on PR (p=0.473). Significant differences were observed in EMR (p=0.008), being higher in the Holstein breed (18/147, 12.2±1.9). No significant differences were observed in pregnancy losses at Day 60 irrespective of the breed (p>0.05). The PR in 4th to 7th stage transferred embryos was 33.4, 30.5, 37.2, and 40.6%, respectively, being higher in 6th and 7th stage blastocysts compared to any other developmental stage (p