Handmade biopsy for genotyping of in vitro-produced bovine embryos.
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Blastocyst biopsy allows genomic selection of pre-implantation bovine embryos, reducing generation interval and enhancing the genetic gain. We aimed to evaluate the suitability of a simple biopsy procedure, performed by hands, using a splitting microblade and a stereoscope, on in vitro-produced embryos. Crossbred Bos taurus x B. indicus blastocysts at Day 6 or 7 after in vitro fertilization (IVF) were biopsied and cultured in vitro for 48h. Biopsy reduced (p<0.01) embryo development as noted by the lower blastocoel formation/re-expansion rates in both Day 6 (33.3% vs. 71.4%) and Day 7 (66.6% vs. 89.8%) blastocysts, when compared to non-biopsied embryos. Biopsy on Day 7 decreased (p<0.01) cell number (112.8±6.3 vs. 149.9±5.6) and increased (p<0.01) apoptotic index (14.9±1.4 vs. 6.2±1.2). In a second experiment, the IVF blastocysts were biopsied in the farm, and cultured for 3h. Re-expanded blastocysts, corresponding to 78.3% biopsied embryos, were transferred to synchronized recipients. Pregnancy (57.4% vs. 62%), delivery (51.0% vs. 48%), gestation length (285.5±2.0 vs. 284.6±1.2days) and birthweight (30.5±1.8 vs. 29.9±1.2kg) were similar (p>0.05) between handmade biopsy and non-biopsied embryos. Whole genome amplification of biopsied samples resulted in 256.0±155.9ng/μL DNA. The mean call rate was 75.3%±4.3% and the imputed GEBV for 305-day milk yield was 839.21±61.6kg. In conclusion, handmade biopsy can be performed at small laboratories and at farm level, contributing to reduce costs for embryo genomic selection. Pregnancy, calf delivery and birthweight were not compromised, and samples are suitable for downstream applications such as genotyping.
Palabras clave
Blastocisto, Seleção genômica, Fertilizacao in vitro, Bovino, Reprodução Animal, Biopsia, Parto