Seven feed ingredient samples including corn, soybean meal (SBM), distillers dried grains with solubles (DDGS), whey permeate, whey powder, spray-dried porcine plasma (SDPP), and fish meal (FM) were ground (<1 mm) and analyzed for the LOD using a forced-draft oven (FC-PO-150, Dongseo Science Ltd., Seongnam, Korea). The methods used to determine of the LOD of the samples included drying at 135°C for 2 h (AOAC, 2005 ; method 930.15), and drying at 105°C for 3 h (Shreve et al., 2006 ; NFTA 2.2.2.5) in triplicate. Additionally, the samples were dried at 105°C for 6, 9, 12, or 15 h in triplicate. The corresponding drying temperature and time applied for a mixed diet which was prepared for the additivity test of LOD and consisted of corn 20%, SBM 10%, DDGS 30%, whey permeate 20%, whey powder 10%, SDPP 5%, and FM 5%.