Bioelectrical Impedance Analysis as a Non-Invasive Approach to Estimate In Vivo Body Composition in Rabbit Does Across Physiological Stages

This study aimed to develop and validate bioelectrical impedance analysis (BIA)-based prediction equations for estimating the in vivo body composition of reproductive rabbit does across different physiological stages. A total of 87 New Zealand × Californian does were used to generate calibration models and 25 additional does served for independent validation. Animals were categorized according to reproductive status (nulliparous, pregnant–lactating, pregnant–non-lactating, non-pregnant–lactating, and non-pregnant–non-lactating). BIA measurements were obtained using a Quantum II analyzer, and chemical composition was determined by proximate analysis. Multiple linear regression models were developed, and equations were validated through relative mean prediction error (RMPE). Significant effects of physiological status were observed on body composition: pregnant–lactating does showed the highest water content, while non-pregnant–non-lactating females exhibited the greatest protein and fat concentrations. Fat and energy contents decreased markedly (−24% and −32%, respectively) during lactation, indicating intense metabolic mobilization. Regression models revealed strong correlations between impedance parameters and chemical composition. Validation confirmed high predictive accuracy (RMPE 15–25%), with crude protein slightly underestimated (3-4%). These findings confirm that BIA provides a reliable, non-destructive alternative to comparative slaughter for assessing body composition in breeding rabbit does throughout the reproductive cycle.