Mesenchymal stem cells (MSCs) have restricted life spans in vitro and can therefore only be expanded for a limited number of cell divisions before entering a senescent state and unequivocally stopping proliferation. Several types of cell culture systems have been used for large-scale expansion of MSCs. A recent trend in cell culture has been the change from serum-use to serum-supplement media. This study was conducted to investigate the proliferative effects of vegetable resources (VR) on equine adipose tissue-derived mesenchymal stem cells (eAD-MSCs) in the absence of serum and their possible mechanisms of action. Regulation of cell cycling is a key process involved in the fate of stem cells, including renewal and differentiation. In this study, we observed that the viability of eAD-MSCs was increased significantly when treated with VR under serum-free conditions. We also observed that expression levels of cell cycling-related proteins such as p53 and p21 were decreased, and proliferating cell nuclear antigen increased significantly in response to treatment with VR in eAD-MSCs under serum-free conditions. Furthermore, expression levels of cell survival-related proteins were increased in response to treatment with VR in eAD-MSCs under serum-free conditions. Therefore, our results suggest that VR promotes proliferation of eAD-MSCs under serum-free conditions.