Technical Abstract: Visible/NIR spectroscopy has the potential to determine key wavelengths for bile detection on droppings. These wavelengths can be used for further development with hyperspectral and/or multispectral imaging methods for real-time monitoring broilers infected by Salmonella. From the preliminary test using droppings only, the wavelengths (absorbance) which represent spectral characteristics of droppings were 448, 978, 1,192, 1,460, 1,780, and 1,910 nm, respectively. However, the peak wavelengths (absorbance) for bile samples were 430, 662, 1,460 and 1,910 nm, respectively. According to the validation test with mixture of droppings with bile samples at three (0.5 mL, 1.0 mL and more than 1.1 mL) concentration levels, the key wavelengths (absorbance) of 448, 662, 978, 1,192, 1,460, 1,780, and 1,910 nm were identified. Based on the preliminary results, the reflectance wavelength of 544 nm can be used for color band for the bile detection on droppings using a machine vision technique.