| Autor: |
Kawamoto TS; Department of Veterinary, Federal University of Uberlandia, Uberlandia 38400-902, MG, Brazil., Viana JHM; Animal Reproduction Laboratory, Embrapa Genetic Resources and Biotechnology, Brasília 70770-917, DF, Brazil., Pontelo TP; Department of Veterinary, Federal University of Lavras, Lavras 37200-900, MG, Brazil., Franco MM; Animal Reproduction Laboratory, Embrapa Genetic Resources and Biotechnology, Brasília 70770-917, DF, Brazil., de Faria OAC; Department of Veterinary, University of Brasilia, Brasília 70910-900, DF, Brazil., Fidelis AAG; Department of Veterinary, University of Brasilia, Brasília 70910-900, DF, Brazil., Vargas LN; Department of Biology, Federal University of Uberlandia, Uberlandia 38400-902, MG, Brazil., Figueiredo RA; Animal Reproduction Laboratory, Embrapa Genetic Resources and Biotechnology, Brasília 70770-917, DF, Brazil. |
| Abstrakt: |
The purpose of this study was to characterize the reproductive physiology, oocyte competence, and chromatin compaction in Nelore calves in the early-prepubertal period (EPP) and the intermediate-prepubertal period (IPP). Calves aged 2-5 (EPP) and 8-11 months old (IPP) were assigned to Trial 1 (morpho-physiological-endocrine evaluations, n = 8) or Trial 2 (oocyte donors, n = 8) vs. the respective control groups of cows (n = 8, each). All morphological endpoints, except the antral follicle count, increased from the EPP to the IPP. The EPP LH-FSH plasma concentrations were similar to cows, whereas LH was lower and FSH was higher in the IPP than in cows. . Cows produced more Grade I (12.9% vs. 4.1% and 1.7%) and fewer Grade III COC (30.1% vs. 44.5% and 49.0%) than the EPP and IPP calves, respectively. The IPP calves' oocyte diameter was similar to those from cows but greater than those from EPP females (124.8 ± 8.5 and 126.0 ± 7.5 μm vs. 121.3 ± 7.5 μm, respectively). The expression of the chromatin compaction-related gene HDAC3 was downregulated in calves. The proportion of the blastocyst rate to the controls was lower in EPP than in IPP calves (43.7% vs. 78.7%, respectively). Progressive oocyte competence was found during the prepubertal period, which can help to decide whether to recover oocytes from calves. |
