210 Prematuration does not improve developmental competence of prepubertal-bovine oocytes
L. O. Leme A , N. R. Kussano B , O. A. C. Faria B , C. F. Martins C and M. A. N. Dode AA Embrapa Genetic Resources and Biotechnology, Brasília, DF, Brazil
B University of Brasilia, Brasília, DF, Brazil
C Embrapa Cerrados, Brasília, DF, Brazil
Reproduction, Fertility and Development 35(2) 234-234 https://doi.org/10.1071/RDv35n2Ab210
Published: 5 December 2022
© 2023 The Author(s) (or their employer(s)). Published by CSIRO Publishing on behalf of the IETS
Considering that oocytes from pre-pubertal females have lower development capacity compared with those of adult cows, a search for new alternatives to improve in vitro embryo production from those oocytes has increased in recent years. Therefore, the aim of the present study was to evaluate whether adding a step before in vitro maturation (IVM), a prematuration period (PIVM) providing extra time to oocytes acquire competence, would improve embryo development. Cumulus-oocyte complexes (COC) were retrieved from 7.5–8.5 month-old prepubertal Nelore calves (preP, n = 38 animals) and from multiparous Nelore cows (Pub, n = 25 animals) via ultrasound-guided follicular aspiration. Recovered oocytes were evaluated, selected, and distributed into four treatments: T1 Control Cows, COC from cows were IVM for 22 h (n = 125); T2 Control preP, COC from prepuberal calves were IVM for 22 h (n = 166); T3 Cows, COC from cows were submitted to PIVM for 6 h followed by 22 h of IVM (n = 96); and T4 preP, COC from preP calves submitted to PIVM for 6 h followed by 22 h of IVM (n = 160). PIVM media was supplemented with NPPC and scriptaid. Immature oocytes were matured in vitro, then fertilised and cultured up to Day 8. Data were analysed by chi-square, considering P ≤ 0.05. The mean number of recovered oocytes/OPU was similar between Pub (16.7) and preP (14.6), being the percentage of viable COCs was also similar between both groups (Pub: 74.53% and preP: 66.06%). No differences (P > 0.05) were observed between Pub and preP in cleavage rate when PIVM was used (78.1% and 73.1%) or not used (86.1% and 80.0%). However, blastocyst development rate at Day 7 (40.0% × 20.5%) and Day 8 (48.9% × 25.8%) was greater (P > 0.05) in oocytes from Pub females than in those from preP females. The use of PIVM did not improve (P > 0.05) embryo outcomes at Day 7 and Day 8 in Pub (43.8% and 47.9%) or in preP (18.1% and 24.4%). We concluded that the inclusion of 6 h PIVM phase did not result in an enhanced developmental competence of oocytes obtained from juvenile females.
This research was supported by CAPES, CNPq, FAPDF, and Embrapa.
