Production of sexed calves from frozen-thawed embryos

Abstract

Three experiments have been conducted with the aim of producing calves from frozen, sexed embryos by combining embryo splitting and cytogenetic methods. In the first experiment, the efficacy of the bisection technique was assessed by transcervical transfer of 10 monozygotic pairs of half embryos to 10 synchronised heifers. Thirteen calves were produced, including four sets of identical twins. In the second experiment, one of the halves of each of eight split embryos was transferred while the other was processed for sexing by identification of the sex chromosomes. In the third experiment, one of the halves from each of 28 embryos was frozen while the other half was used for sexing. Eleven of the 16 which were sexed have been transferred with the production of three calves of the predicted sex. The overall sexing rate was 60 per cent and the calving rate following transfer of sexed embryos was 60 per cent and 23 per cent for fresh and frozen halves respectively.

Sex of IVM, IVF and IVC Blastocysts Produced from Individual Donor Cows.

“…In some previous studies, no significant difference was found in the developmental rate of male and female embryos from morula to hatched blastocyst in IVM, IVF, and in vivo developed embryos [3,5], while a significant difference was found in IVM, IVF, and IVC derived embryos [4,6]. King et al [20] and Picard et al [21] reported that there was no difference in the sex ratio of calves produced from in vivo-derived embryos. However, in embryo transfer experiments, Itoh and Goto [2] found that faster development of male embryos and slower development of female embryos was seen by grouping the developmental stages of embryos from each donor cow.…”

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“…In addition, poor spreading and over scattering of metaphase chromosomes have been noted as a major problem of embryo sexing by karyotyping. 19 However, the major advantages of karyotyping are; 1) it is inexpensive and easy to perform, 2) it requires no sophisticated equipment, and 3) it can identify chromosomal anomalies before the embryos are transferred. The percentages of bovine embryos at 5 days after insemination which could be sexed by karytyping are similar in the cell numbers ranging from 4 to 95.…”

Effect of Administration with Low-dose FSH to Recipient Cows on Embryonic Survival after Bilateral Nonsurgical Embryo Transfer.

“…Therefore, it can be concluded that each embryo bilaterally distributed to uterine horns influences the other. Furthermore, it may be postulated that mutual help from two embryos produces more efficient luteotrophic (luteostatic) and/ or antiluteolytic messages to maintain pregnancy [31,32].…”