Estimation of body composition of pigs by a near-infrared interactance probe technique

Near-infrared (NIR) interactance was evaluated as a potentially new method for estimating live body and carcass composition of pigs. Using a surface placed fiber optic probe, measurements of the live animal and carcass were made on a total of 120 pigs. These measurements were compared with lipid and protein content of soft tissue dissected from the pig carcass. NIR results were evaluated using multiple regression equations containing NIR readings at various locations on the body, combinations of wavelengths and with or without ultrasonic fat depth readings and body weight. NIR measurements made on the carcass predicted percent carcass fat (R = 0.71) better than did measurements made on the live animal (R = 0.66), however, both could be improved substantially by including live body weight in the prediction equation (R = 0.93 and 0.91). Spectral information indicated that the depth of tissue penetration and reflectance may be the primary limitation in this application of the current technology.