An evaluation of the Hennessy Grading Probe for measuring fat depth in beef carcasses

Abstract

Fat depth at the P8 site on the rump was measured by the cut-and-measure (CM) technique and with the Hennessy Grading Probe (HGP) on 2501 beef carcasses at 1 abattoir over a 12-month period. CM measurements that differed by more than 1 mm between the right and left sides of the carcass were discarded. A subsequent data set of 1850 carcasses was randomly divided so that 2 models could be developed to assess the general validity of the relationship between the 2 methods of measurement. Analysis of measurements of the left side of the carcasses of these 2 subsamples showed the data were not normally distributed. Removal of outliers at the 95% confidence level and also measurements at both extremes of the data range improved the symmetry of the sets of data. From each adjusted data set, regression equations were developed to predict CM measurements from HGP measurements. Linear equations were adequate for predicting CM measurements from HGP measurements, and curvilinear analysis did not improve the predictions. Compared with the curvilinear equations, the linear equations resulted in smaller differences between the 2 data sets for the predicted CM measurements over a range of HGP measurements.