Determination of RN(-) phenotype in pigs at slaughter-line using visual and near-infrared spectroscopy

The specific characteristics of meat from the Hampshire breed of pig, including high glycogen content and low ultimate pH and technological yield, have been associated with the dominant RN gene. In Sweden, purebred Hampshire or Hampshire x Yorkshire is often used as terminal sire in the three-way crosses used for pig meat production. For the industry producing cured and cooked hams there is a need to detect the RN(-) carriers of the pigs early post mortem in order to select non-carriers for ham production. In the present study, the possibility of separating RN(-) carriers from non-carriers using a combination of visual and near-infrared (NIR) spectroscopic measurements in reflectance mode through a fibre-optic probe has been studied on commercial pigs in a slaughterhouse. The NIR measurements were performed 30 min post-mortem. Sixty-three animals were considered to be carriers and 33 animals non-carriers based on their glycolytic potential in M. semimembranosus (above 200 μmol/g for RN(-)rn(+) and below 180 μmol/g for rn(+)rn(+)). By using NIR together with classification with neural networks, RN(-) carriers could be separated from non-carriers. None of the carriers and only four non-carriers of the RN gene were misclassified as carriers of the RN gene. The ultimate pH could be predicted using linear partial least squares regression with a correlation coefficient of 0.57 and an accuracy of 0.074 root mean square error of prediction.