Born Simmental calves after the transfer of genetic evaluated day 7 bovine embryos

Genomic selection can theoretically take place in any stage of an animal’s life. The use of ET can increase the intensity of selection, but at the cost of keeping many recipients. This can be avoided by transferring only embryos with desired gender and best breeding values. Improvement of embryo micromanipulation and DNA amplification techniques allows for the direct genetic analysis of bovine embryos prior to implantation. The aim of our study was to set up and optimize a whole embryo production and evaluation line in Simmental cattle to determine gender, polled status, hereditary defects and reliable breeding values on blastomeres at the morula and blastocyst stages. For embryo recovery (n=45) German Simmental animals (n=17) were superovulated using a standard protocol. Embryos were biopsied immediately after recovery by a single operator under a mobile stereo microscope (Olympus) at 50x magnification with a single use special steel blade mounted on a blade holder (Bausch & Lomb, Germany) attached to a micromanipulator (Eppendorf, Germany). Two biopsy methods were compared, first embryos were splitted and one third of a half cut off (G1, n=161) or by cutting of the trophoblast (G2, n=146). Biopsied cells, approximately 10-15, were immediately used for whole genome amplification (Repli-g mini Kit, Qiagen) followed by PCR analysis of gender and polledness. Hereditary defects were analyzed using a 5’-exonuclease assay. Embryos were transferred to recipients after in vitro culture in SOF supplemented with 5% ECS, 40 µl/ml BME and 10 µl/ml MEM in fourwell dishes, under mineral oil, at 39°C and gas mixture (5% CO2, 5% O2, 90% N2) for 24 h. DNA of the first 14 born calves was extracted from blood samples. These calves together with the corresponding embryos were genotyped with the Illumina Bovine 54k BeadChip. Call rates were recorded, correlations between embryo and calf genotypes calculated and breeding values estimated. The biopsy technique G1 resulted in the highest number of good quality transferable embryos G1 (1.37) vs. G2 (0.97) (p<0.05) in relation to the number of original embryos. However, better pregnancy rates were obtained by transferring 2 demi-embryos to one recipient (1 demiembryo=28.6%; 2 demi-embryos=76.2%). Biopsy technique G2 resulted in 55.0% pregnancies. No discrepancies could be detected between gender, polled and hereditary defect status of born calves and corresponding embryos. The average call rate for the genotyped embryos was 0.922, ranging from 0.841 to 0.980. The call rate of the corresponding calves ranged from 0.998 to 0.999. The average concurrency of the obtained genotypes of embryos and calves was 98.7%, with an average correlation of 0.991. Gender, polledness and genotypes obtained from preimplanted embryos were consistent with genotypes obtained of the born calves. Therefore, our first results provide promising prospects for the optimized production line.