PERTANIKA JOURNAL OF TROPICAL AGRICULTURAL SCIENCE

Pretreatment techniques have been widely used to improve the quality of animal feed ingredients. In the current study, the chemical composition and the physicochemical properties of treated corn grain (extrusion, microwave irradiation, gamma irradiation, or NaOH hydrolysis) were investigated. The in vitro digestibility was evaluated using digestive enzyme extracts from Nile tilapia (Oreochromis niloticus) and broiler chicken (Gallus gallus domesticus), as well as the pepsin-cellulase technique of the ruminant model. There were notable changes in the chemical compositions (p < 0.001), as well as a nutritive profile assessment with Fourier transform infrared spectroscopy. The extrusion pretreatment significantly increased crude protein and ether extract contents, as well as gross energy. However, this method reduced ash and non-fiber carbohydrate contents while increasing the amount of neutral detergent fiber (p < 0.001). The determination of pH, water solubility, water absorption capacity, and thermal properties, and observation of diffraction patterns and microstructures indicated that the altered physicochemical properties of treated corn enhanced enzymatic hydrolysis. The results of carbohydrate digestibility testing suggested that microwave irradiation or extrusion were the best pretreatments for aquatic animals, while only extrusion was suitable for poultry. However, the pepsin-cellulase digestibility test revealed no differences in cellulase organic matter solubility, digestible organic matter, and metabolizable energy. Therefore, the most suitable pretreatment method for corn grain used in animal feed is dependent on the target animal group.