Prediction of carcass composition by impedance spectroscopy in lambs of similar weight

Application of bioelectrical impedance analysis to assess body composition of male and female broiler chickens from 2 different strains throughout the growth period

Bioelectrical impedance analysis (BIA) was performed in males and females of 2 different broiler strains from 0 to 42 d of age to develop and validate equations to predict body composition (BC). A total of 528 birds, 132 birds per sex and strain (Ross 308 and Cobb 500) were used in the experiment. Birds were fed ad libitum following CVB recommendations with a common starter (0-14 d), grower (15-29 d), and finisher diet (30-42 d). Bioelectrical impedance analysis was measured weekly from 0 to 42 d. Birds were euthanized, frozen and ground for sample collection. Each sample was analyzed through proximate analysis for dry matter (DM), protein, fat, ash, and energy content. Water (%), protein and ash (% DM) decreased with age (77.5-67.5, 69.1-52.2, and 8.12-7.29, respectively; P < 0.0001); whereas fat (% DM) and energy (cal/g DM) increased with the age (20.7-36.4 and 5,421-6151, respectively; P < 0.0001). Males had significantly higher water (%) and protein (% DM) contents, and lower lipid (% DM) deposits than females (70.5, 55.5, and 32.6 vs. 69.6, 54.6, and 33.7, respectively; P < 0.0001). Cobb 500 had a higher fat and lower protein (% DM) and water (%) content than Ross (34.6, 54.0, and 69.7 vs. 31.7, 56.1, and 70.4, respectively; P < 0.0001). A multiple linear regression analysis was carried out to select the equation model to predict BC using the relative mean prediction error (RMPE, %) to evaluate the accuracy. The coefficients of determination (R2) to estimate water (%), protein, fat, ash (% DM) and energy content (cal/g DM) were 0.909, 0.825, 0.795, 0.493, and 0.838, respectively, and the RMPE were 1.26, 3.46, 7.73, 8.85, and 1.86%, respectively. A t test analysis was run, observing no differences in any of the parameters under study between the analyzed and estimated values. Based on these results, we can conclude that BIA can be used as a valid non-invasive technique to estimate in vivo BC in broilers.

Application of Bioelectrical Impedance Analysis (BIA) to Assess Carcass Composition and Nutrient Retention in Rabbits from 25 to 77 Days of Age

The aim of this study was to assess and validate, using independent data, the prediction equations obtained to estimate in vivo carcass composition using bioelectrical impedance analysis (BIA) to determine the nutrient retention and overall energy and nitrogen retention efficiencies of growing rabbits. Seventy-five rabbits grouped into five different ages (25, 35, 49, 63 and 77 days) were used in the study. A four-terminal body-composition analyzer was applied to obtain resistance (Rs, Ω) and reactance (Xc, Ω) values. All the animals were stunned and bled at each selected age, and the chilled carcasses were analyzed to determine water, fat, crude protein (CP), ash and gross energy (GE). Multiple linear regression analysis was conducted to determine the equations, using body weight, length and impedance data as independent variables. The coefficients of determination (R2) to estimate the content of water, protein, fat and ash in grams, and energy in Mega Jules(MJ), were: 0.99, 0.99, 0.95, 0.96 and 0.98, respectively, and the relative mean prediction errors (RMPE) were: 4.20, 5.48, 21.9, 9.10 and 6.77%, respectively. Carcass yield (%) estimation had values of 0.50 and 10.0 for R2 and RMPE, respectively. When water content was expressed as a percentage, the R2 and RMPE were 0.79 and 1.62%, respectively. When the protein, fat and ash were expressed as a percentage of dry matter (%DM) and the energy content as kJ/100 g DM, the R2 values were 0.68, 0.76, 0.66 and 0.82, respectively, and the RMPEs were 3.22, 10.5, 5.82 and 2.54%, respectively. Energy Retention Efficiency was 20.4 ± 7.29%, 21.0 ± 4.18% and 20.8 ± 2.79% from 35 to 49, from 49 to 63 and from 35 to 63 d, respectively. Nitrogen Retention Efficiency was 46.9 ± 11.7%, 34.5 ± 7.32% and 39.1 ± 3.23% for the same periods. Energy was retained in body tissues for growth with an efficiency of approximately 52.5%, and the energy efficiency for protein and fat retention was 33.3 and 69.9%, respectively. This work shows that BIA is a non-invasive and good method to estimate in vivo carcass composition and to determine the nutrient retention of growing rabbits from 25 to 77 days of age.

Application of bioelectrical impedance analysis to assess rabbit's body composition from 25 to 77 days of age

The aim of the study was to develop prediction equations for assessing, in vivo, the whole body composition of growing rabbits. The accuracy of the models obtained was externally validated with independent data sets. One hundred fifty rabbits grouped at 5 different ages (25, 35, 49, 63, and 77 d) were used. A body composition analyzer with 4 terminals was used to obtain resistance (Rs; Ω) and reactance (Xc; Ω) values. The distance between internal electrodes (D; cm), body length (Len; cm), and live BW (g) were also registered. Average values of Rs, Xc, impedance (Z), Len, D, and BW were 83.5 ± 23.1 Ω, 18.2 ± 3.8 Ω, 85.6 ± 22.9 Ω, 30.6 ± 6.9 cm, 10.8 ± 3.1 cm, and 1,454 ± 845 g, respectively. At each selected age, animals were slaughtered, ground, and frozen (-20°C) for determining water, fat, CP, ash, and GE (70.5 ± 3.36%, 27.7 ± 7.61% DM, 54.9 ± 5.41% DM, 11.1 ± 1.55% DM, and 2,267 ± 183 kJ/100 g DM, on average, respectively). Fat and GE contents increased with the age, whereas CP, ash, and water contents decreased. A multiple linear regression analysis was used to determine the prediction equations, using BW, Len, and Z data as independent variables. Equations obtained to estimate water (g), CP (g), fat (g), ash (g), and GE (MJ) had coefficient of determination () values of 0.99, 0.99, 0.97, 0.98, and 0.99, respectively, and the relative mean prediction error (RMPE) was 2.79, 6.15, 24.3, 15.2, and 10.6%, respectively. When water was expressed as a percentage, the and RMPE were 0.85 and 2.30%, respectively. When prediction of the content of protein (% DM), fat (% DM), ash (% DM), and energy (kJ/100 g DM) was done, values of 0.79, 0.83, 0.71, and 0.86, respectively, for and 5.04, 18.9, 12.0, and 3.19%, respectively, for RMPE were obtained. It could be concluded that bioelectrical impedance analysis is a good, noninvasive method to estimate, in vivo, whole body composition of growing rabbits from 25 to 77 d of age.