PREDICTION OF LIVE LAMB CHEMICAL-COMPOSITION UTILIZING ELECTROMAGNETIC SCANNING (TOBEC(TM))(1)

Electromagnetic scanning was investigated to determine its accuracy in predicting chemical composition in live lambs. Forty-seven Rambouille t wether lambs were scanned with an electromagnetic instrument (ToBEC( TM) Model HA-2). Lambs were serially scanned and slaughtered over the weight range of 29.5 to 63.5 kg. Each lamb was scanned twice: before a nd immediately after 24 h of food deprivation. Chemical composition wa s determined from whole-animal ground samples by AOAC methods for perc entage of DM, CP, ether extract (EE), and Ash. Percentage of fat-free mass (FFM) was calculated from the percentage of moisture and CP. Corr elation and stepwise regression procedures were used to identify the m ost reliable independent variables for predicting chemical composition . Independent variables included electromagnetic scan data and live an imal measures for weight, body length, and chest girth circumference. Electromagnetic data included the average scan response curve (PHO) an d Fourier transformations (P1T, P1R, P2T, and P2R). Repeatability of t he HA-2 model was extremely high (r = .98). Reliable prediction equati ons were obtained for DM, CP, EE, and FFM (R(2) > .66). The percentage of ash could not be predicted from the independent variables. Electro magnetic scan responses contributed little to the model sum of squares . Body weight accounted for the majority of the model sum of squares. Depriving lambs of food for 24 h slightly improved the R(2) value and significantly decreased scan responses (P < .01). Body weight was a be tter predictor of chemical composition over a large weight range than any of the scan responses. Further investigation of the HA-2 is needed to determine whether it is effective in determining differences in li ve body composition between animals of equal weight.