Comparison of visible and near infrared reflectance spectroscopy to discriminate between pasture-fed and concentrate-fed lamb carcasses

We compared visible and near infrared spectroscopy to distinguish pasture-fed (P) from stall concentrate-fed (S) lamb carcasses. A total of 120 P and 139 S lambs were used. The reflectance spectrum of perirenal fat was measured at wavelengths between 400 and 700 nm using a portable spectrophotometer, and at wavelengths between 400 and 2500 nm using a laboratory monochromator NIRSystem. In method W450–510, the reflectance data were used at wavelengths between 450 and 510 nm. In methods W400–700 and W400–2500, a multivariate analysis was performed over the full set of reflectance data, at wavelengths in the range 400–700 nm and 400–2500 nm, respectively. The proportion of correctly classified P lambs was 89.1%, 90.8% and 97.5% for W450–510, W400–700 and W400–2500,W400–2500 performing best. The proportion of correctly classified S lambs was not significantly different between methods (98.6%, 98.6% and 97.8% for W450–510, W400–700 and W400–2500, respectively).