Date of Award:

5-2026

Document Type:

Thesis

Degree Name:

Master of Science (MS)

Department:

Animal, Dairy, and Veterinary Sciences

Committee Chair(s)

Kenneth L. White

Committee

Kenneth L. White

Committee

Ying Liu

Committee

Aaron Thomas

Abstract

Serum-containing media has been shown to increase incidence of large offspring syndrome and to alter gene expression, protein synthesis, and cell signaling. These factors together can result in increased pregnancy loss when combined with assisted reproduction technologies. However, there are very few direct comparisons of commercial serum-free media (IVF Bioscience™) and serum-containing media on both IVF and cloned embryo development in cattle. The aim of this study was to determine the role of serum in oocyte maturation and subsequent embryo development. Three culture systems, including in vitro maturation (IVM) and in vitro culture (IVC), were used in this study. Both IVF and somatic cell nuclear transfer (SCNT) embryos were generated with our standard protocols. For in vitro study, IVF and SCNT embryos were assessed for cleavage rates on day 2 and blastocyst rates on day 8. A time-lapse incubator was used to assess embryos individually during culture. All experiments have 3-5 replicates. For in vivo study, biopsy of SCNT embryos was performed at the 12-16 cell stage, removing 2 blastomeres, and the biopsied cells processed for single-cell ATAC-sequencing (scATAC-seq). Following biopsy, SCNT embryos were cultured individually until day 6 and transferred to recipients. In total, 47 biopsied blastocysts from all three culture groups were transferred into 47 recipients. On days 30, 90, and 120 post transfer, pregnancy status was assessed using transvaginal ultrasound. Statistical significance was defined as p< 0.05. Embryos were assessed for difference in maturation, cleavage rates, blastocyst rates, timing of each stage, timing of the first cleavage, timing of the embryos remaining at 8-cell stage, the time embryos stay in the morula stage before transitioning to blastocyst, stages of blastocyst, blastocyst size, cell number, and effect of biopsy on embryo. ATAC-seq was performed on the biopsies from all 47 transferred embryos. Peaks in six genes were selected for analysis. In conclusion, commercial serum-free media improves the cleavage of SCNT embryos, whereas adding serum into these media accelerates the blastocyst formation. Preliminary ATAC sequencing results show no significance in EGA score, which may indicate a serum-free medium has no impact on early gene expression profiles.

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