Prediction of whole-body protein and lipid deposition and energy requirement in live pigs based on bioelectrical impedance and heart rate monitoring

Accurately estimating whole-body protein (P d ) and lipid (L d ) deposition and energy requirement in live pigs is essential for growth monitoring and improving the utilization efficiency of feed. Traditional approaches rely on large-scale equipment such as computed tomography and respiration chambers, which are labor-intensive and costly, and often impractical for routine use. Therefore, this study aimed to predict dynamic changes in P d , L d , and energy requirement using portable methods, including bioimpedance analysis (BIA), segmental BIA (SBIA), and heart-rate (HR) monitoring. Twelve Duroc × Landrace × Yorkshire barrows served as experimental replicates. Six pigs entered the trial at 12 weeks of age (34.0 ± 2.5 kg of body weight) and another six at 16 weeks (56.8 ± 7.5 kg of body weight). The pigs completed 18 consecutive 4-d calorimetric cycles (3 d fed and 1 d fast) over 72 d, generating 54 repeated records of heat production and energy balance through indirect calorimetry combined with a digestion-metabolism assay. Concurrently, a single-frequency segmental impedance analyzer and a custom heart-rate vest continuously collected impedance and HR variables. Prediction models on P d , L d , and energy requirement were established using stepwise regression based on different predictors selected, and the best-fitted prediction models were identified and evaluated through cross-validation. It was found that whole-body resistance (W-Body Rs) from SBIA correlated strongly with P d ( r = –0.59 and P < 0.001). Best-fitted models for P d , L d , total heat production, fasting heat production, total net energy (NE) requirement, and NE for deposition achieved R 2 values of 0.784, 0.873, 0.952, 0.885, 0.943, and 0.901, respectively ( P < 0.05). Thus, non-invasive SBIA and HR offer excellent potential for real-time estimation of P d and L d , as well as energy requirement in live pigs.