Reproductive aging in mares is associated with a decrease in the quality and quantity of oocytes, which is the limiting factor in the production of embryos in vitro. Nicotinic acid (NA) is a key precursor of nicotinamide adenine dinucleotide (NAD+), which is involved in energy metabolism, cell survival, and DNA repair. Studies in mice and pigs have shown that NAD+-elevating treatments during in vitro maturation (IVM) improve oocyte developmental competence [1,2]. This study aimed to evaluate the effect of NA treatment on equine oocyte quality by assessing the development of embryos produced by somatic cell nuclear transfer (SCNT). Cumulus-oocyte complexes (COCs) collected from slaughterhouse-derived ovaries were washed and transferred to cryovials filled with a 1:1 mixture of DMEM-F12 and TCM-199 containing 10% FCS and kept at 20-22°C. Groups were either untreated (control) or treated with 50 and 200 µM NA for 18 h. Immature oocytes from the three groups were then washed, transferred to maturation medium, and incubated for a further 18 h at 38.5°C in 5% CO2. A total of 694 oocytes were matured in 6 replicates. The methods used for IVM, SCNT, and embryo culture were identical for all three groups. The rates of meiotic maturation, fusion, cleavage, and embryonic development were evaluated. Data were subjected to ANOVA and Tukey’s test. The rates of maturation, couplet fusion and cleavage were similar for the three groups (P>0.05). Day 7 blastocyst formation rates were greater for the treatment groups, 50 (27.1 ± 1.4%) and 200 µM NA (32.9 ± 3.0%), compared to the control group (19.9 ± 1.7%; P<0.05). The results show that NA supplementation improved the development of equine cloned embryos. Further studies are needed to reveal the cellular benefit of elevating NAD+ during the pre-maturation period and to determine embryo viability in vivo after transfer to recipient mares.