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.

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Selenium (Se) is an essential nutrient with multiple human health benefits; the single most important dietary source of Se is beef. The Se content of beef varies, and cattle fed a high selenium diet may have Se concentrations in beef that are well above average. Such beef is potentially a unique supplemental source of dietary Se. To examine factors affecting Se accumulation in beef, 16 steers (initial wt 374.4 +/- 33.7 kg) were taken from seleniferous or nonseleniferous areas and fed in a 2 x 2 factorial design with diets high or moderate in Se (11.9 or 0.62 mg Se/kg diet). Diets contained 50% alfalfa, 25% wheat, and 25% corn on a dry matter basis. All dietary Se was from agricultural products, and Se in the high Se diet was primarily from high Se wheat and alfalfa hay. A loin muscle biopsy was taken at the start of the trial to determine initial Se content of beef. Steers were slaughtered after 14 weeks of the trial, and edible carcass (round, sirloin, shoulder clod, and ribeye) and organ samples were collected. Diets did not affect growth or feed intake (P > 0.05), and Se toxicity signs were not observed. Different cuts of meat had similar Se concentrations, and the Se content of all cuts was increased by both high dietary Se and high Se background. Except for liver and kidney, Se in tissues was increased by seleniferous background (P < 0.02) and high dietary Se (P < 0.001). Kidney Se concentrations of animals fed the high Se diet were lowest in animals from seleniferous areas (P = 0.04), suggesting a possible adaptation to the high Se diet. These results demonstrate that cattle fed diets high in Se from agricultural products will accumulate substantial amounts of Se in the beef without developing signs of Se toxicity and that prior Se status regulates Se accumulation in some organs. They further demonstrate that management practices may be altered so as to make beef a significant source of dietary Se.