Epigenetic memory, reinforced by redundant heterochromatic networks, is a major barrier to somatic cell reprogramming. In cattle, single-agent chromatin-modifying treatments show inconsistent efficacy, likely due to compensatory crosstalk among repressive marks. Here, we evaluated a multi-target small-molecule cocktail, GUSTC, combining G SK343 (EZH2 inhibitor), U NC0638 (G9a/GLP inhibitor), S odium Butyrate (HDAC inhibitor), T richostatin A (HDAC inhibitor), and C haetocin (SUV39H1 inhibitor) to simultaneously target facultative and constitutive heterochromatin in bovine fibroblasts. At optimized, non-cytotoxic concentrations, GUSTC treatment reduced H3K9me2, H3K9me3, H3K27me3, and HP1-alpha levels while increasing H3K9 acetylation by immunofluorescence. Using GUSTC-treated fibroblasts as donor cells for somatic cell nuclear transfer did not significantly change cleavage (83.6% vs. 92.2%; p = 0.15), blastocyst rate (28.4% vs. 39.0%; p = 0.20), bovine embryonic stem cell line derivation efficiency (26.3% vs. 33.3% of seeded blastocysts; p = 0.57), or the core pluripotency marker profile (OCT4, NANOG, SOX2) of the resulting lines. In a separate, serum-free, pluripotency-permissive culture system, GUSTC-treated cells adopted a colony-like morphology and showed increased POU5F1 and NANOG expression, along with increased DNMT1, EHMT2, HDAC1, HDAC2, and SUV39H1 transcripts. GUSTC thus reduces repressive heterochromatin marks in donor fibroblasts and is associated with a potentially more reprogramming-permissive state, without detectable improvement in preimplantation developmental competence. It provides a starting point for chemical reprogramming strategies in cattle. Summary sentence A small-molecule cocktail lowers H3K9me2/3, H3K27me3, and HP1-alpha in bovine fibroblasts and increases POU5F1 and NANOG expression in serum-free culture, without improving cloned blastocyst development or embryonic stem cell establishment. Graphical abstract Proposed model: GUSTC treatment lowers repressive histone marks in bovine fibroblasts and, in serum-free culture, is associated with colony-like morphology and POU5F1 and NANOG expression. In the model, GUSTC inhibits EHMT2, SUV39H1/2, EZH2, and HDACs, relieving repression and allowing H3K9 acetylation (AC); Me2/Me3, di-/trimethylation. In contrast, SCNT with GUSTC-treated donor fibroblasts did not significantly change cleavage, blastocyst development, or bESC derivation compared with control. Alt text: Schematic titled "Proposed model". Left: timeline in which bovine fibroblasts in Alpha-MEM with 10% FBS are moved to KnockOut-DMEM/F12 with 20% KSR and GUSTC, form colony-like structures, and show increased plasticity. Center: in the top panel, EHMT2, SUV39H1/2, and the EZH2-containing PRC2 complex with HP1 add methyl groups to H3K9 and H3K27 while HDAC removes acetylation, so pluripotent genes are silenced; in the bottom panel, GUSTC blocks these enzymes, H3K9 is acetylated, and POU5F1 and NANOG are on. Right: timeline in which fibroblasts in Alpha-MEM with 10% FBS plus GUSTC are used for nuclear transfer embryos and bovine embryonic stem cell colonies, with no significant change compared with control.