Oleum cinnamomi (OCM, cinnamon oil), which is produced by aromatic cinnamon plants, is increasingly used as a feed additive to animal diets. OCM is a natural product rich in polyphenolic compounds that exhibit strong antioxidative property. However, the direct addition of OCM to the feed is questionable due to several limiting physical–chemical factors such as the high hydrophobicity, volatility, odor, fast decomposition, and poor availability in the lower gastrointestinal tract of animals. Therefore, the coated form of OCM (cOCM) is one of th...