Prostate androgen-regulated mucin-like protein 1 (PARM1) is an anti-apoptotic glycoprotein involved in the endoplasmic reticulum (ER) stress response. A single nucleotide polymorphism in the coding region of PARM1 has been associated with competence of bovine embryos to develop to the blastocyst stage. The importance of PARM1 for development was tested by evaluating consequences of reducing PARM1 mRNA abundance on embryonic development and differentiation, gene expression and resistance to heat shock. Embryos produced in vitro were treated with 5 µM GapmeR antisense oligonucleotide targeting PARM1 (knockdown; KD), 5 µM scrambled GapmeR (scrambled; SC), or vehicle (VEH) at 22 h after insemination. All experiments were performed in 4 replicates. In experiment 1, percent of putative zygotes that cleaved or became blastocysts was not affected by treatment; however, KD PARM1 decreased number of trophectoderm cells (P < 0.04) and increased number of inner cell mass cells (P = 0.09). In experiment 2, compact morulae and blastocysts were collected on Days 5 and 7 of culture, respectively, to evaluate expression of 100 genes related to embryonic differentiation, chemokine signaling, epigenetic modification, cell polarity, and ER stress modulation. KD decreased PARM1 expression for morulae (P = 0.05) and blastocysts (P < 0.0007). In addition, KD increased (P ≤ 0.05) transcript abundance for DAB2, INDL, KLF4, STAT3 and reduced (P = 0.03) transcript abundance for CCR2 in morulae. In blastocysts, KD increased (P ≤ 0.05) transcript abundance for PECAM and TEAD4 and decreased (P = 0.03) abundance for CCR7. In experiment 3, embryos from each treatment were subject at d 5 of culture to either heat shock of 41°C or to control temperature of 38.5°C for 24 h; blastocyst formation was assessed on d 7 of culture. Heat shock decreased (P = 0.07) blastocyst formation but there was no effect of PARM1 KD or interaction with heat shock. Results indicate that PARM1 participates in formation of TE and is involved in regulation of expression of genes important for embryonic development. Research supported by USDA-NRI AFRI 2013-68004-20365 and BARD US-4719-14.