Dynamics of Predictors of Body Reserves of Goats in Negative Energy Balance

Abstract

This study aimed to evaluate the relationship between body weight and body condition score with changes in protein and fat reserves in goats during the negative energy balance. Twenty-four goats were distributed in a completely randomized design, with four different Body Condition Scores (BCS): 3.5, 3.0, 2.5, and 2.0. Five experienced evaluators assessed the BCS by palpating two measurements (lumbar and sternal region). The animals' weight was determined every seven days to check weight loss or gain. The goats were slaughtered to assess body fat and protein contents. The BCS did not affect (p>0.05) the goats' performance. The BCS showed a lower precision (R2 0.34) to estimate the protein contents of the noncarcass components compared to the carcass (R2 0.61). The R2 values were better for fat in the carcass, empty body, and non-carcass, displaying values of 0.77, 0.75, and 0.72, respectively, BCS proved to be a good predictor. Body weight proved to be a good predictor for estimating protein in the carcass (R2=0.88), empty body (R2=0.86), and non-carcass (R2=0.99). Therefore, BCS and body weight proved to be good estimators for the body fat reserves in goats at the beginning of lactation. Body weight proved to be more accurate than BCS for determining body protein. BCS and body weight are very important and quick tools to evaluate the nutritional plans implemented in the production system, contributing to increase the efficiency in milk production and the animals' body condition recovery after the negative energy balance.