Development and evaluation of equations to predict body weight of Pelibuey ewes using heart girth

Abstract

The aim of this study was to develop and evaluate equations to predict body weight (BW) using heart girth (HG) in Pelibuey ewes. For model develop a data set composed by 366, 3-year-old, non-pregnant and non-lactating ewes; with a mean BW of 45.7±9.16 kg and HG of 87.55± 7.93 cm was used. A linear equation was fitted: BW= -47.97 (±2.01*) + 1.07 (±0.02**)×HG (R2 = 0.86, RMSE = 3.46, , y n = 366). A second data set composed by 67 animals, with similar characteristics (BW of 38.25± 8.62 kg and HG of 80.37± 7.03 cm) was used to evaluate the developed equations. For the evaluation, the relationship between observed and predicted values of BW by linear regression, the mean squared error of prediction (MSEP) and root MSEP (RMSEP), and concordance correlation coefficient analysis were used. The proposed equation was highly precise (r2 =0.913) and accurate (Cb=0.996) with a reproducibility index of 0.95. The MEF have indicates a higher efficiency of prediction with higher proportion of the total variance of the observed values been explained by the predicted data (0.91). The partition of the MSEP have indicated a very small mean bias (0.082). The systematic bias have shown that only 1.93% of the error of prediction was associated with the slope and most of the error was explained by the random component indicating small biases with the predictions. The proposed equation accurately and precisely estimated the BW of Pelibuey ewe using HG and therefore is recommended to be used.