Bioelectrical impedance: a nondestructive method to determine fat-free mass of live market swine and pork carcasses3

Abstract

Ninety-two swine averaging 104 +/- 4.5 kg and 99 cold carcasses averaging 75 +/- 3.1 kg were measured with a four-terminal plethysmograph. Pigs were transported to the abattoir, fasted 4 h, weighted, and measured for body resistance (Rs, omega), body reactance (Xc, omega), and distance (L, cm) between detector terminals that were located along the dorsal axis of the animal. Pigs were slaughtered 12 h later, carcasses were chilled for 24 h, then weighted (whole carcasses and side carcasses), and cold carcass Rs, Xc, and L measurements were obtained. The right side of the carcass was ground twice, and a 1-kg sample was frozen for later analyses of fat, ash, N, and moisture. Fat-free mass (FFM, kg) was calculated from weight and percentage of fat. Regression analyses were used to develop equations for estimating FFM on a live, adjusted live, whole carcass, and half-carcass basis. Live BW, Rs, and L accounted for the majority of the variation in FFM. Adjusting live BW for head, viscera, and blood weight increased the explained variation for live BW and decreased the variation accounted by Rs. Multiple regression models involving Rs, L, Xc, and weight accounted for 82, 84, and 84% of the variation for FFM expressed on a live, adjusted live, and cold carcass basis, respectively. Results from this study indicate that bioelectrical impedance has excellent potential as a rapid, nondestructive method for estimation of FFM for market swine and pork carcasses.

Relationships among dual-energy X-ray absorptiometry, bioelectrical impedance and ultrasound measurements of body composition of swine

“…The correlations between DXA and BF measurements were higher at 110 kg than at 60 kg, whereas they were lower for DXA and LMA. Rs BIA resistance measurement, Xc BIA reactance measurement, BIA-FFM fat free lean mass calculated using the BIA model of Swantek (1992), LMA longissimus muscle area, BF P2 backfat depth, US-FFM fat-free lean mass calculated using the NPPC (1999) formula, SD standard deviation, * P<0.05, ** P<0.01, *** P<0.001…”

“…In addition to the DXA measurements, results of the ultrasound measurements of BF and LMA are shown in Tables 1 and 3 and results of the BIA measurements are shown in Tables 2 and 3. LMA longissimus muscle area, BF P2 backfat depth, US-FFM fat-free lean mass calculated using the NPPC (1999) formula Rs BIA resistance measurement, Xc BIA reactance measurement, BIA-FFM fat free lean mass calculated using the BIA model of Swantek (1992), LMA longissimus muscle area, BF P2 backfat depth, SD standard deviation…”

“…The four needle electrodes were implanted as described by SWANTEK et al 1992). Fat-free lean mass (FFM, kg) was calculated using Rs, Xc, live weight (LWt, kg), and body length (L, cm), based on the model reported by SWANTEK et al (1992):…”

“…Once the electrodes are in place, the impedance readings (Rs and Xc) are taken. The study by SWANTEK et al (1992) reported correlations of −0.56 and −0.63 between Rs and fat-free mass (FFM) and 0.64 and 0.70 between Rs and percentage fat for live and carcass measurements, respectively. The correlations were not as good for Xc (−0.11, −0.08, −0.11, and 0.17, respectively).…”

“…In limited studies, BIA has been used to predict the fat-free mass of live pigs and carcasses (SWANTEK et al 1992) and the Boston butt portion of pork carcasses (MARCHELLO & SLANGER 1992). It has also been tested for measuring the fat-free mass of lambs and lamb carcasses (BERG & MARCHELLO 1994, BERG et al 1996, HEGARTY 1998, SÜSS et al 2001, and the composition of steer carcasses (VELAZCO et al 1999).…”