EVALUATION OF A PREDICTION EQUATION OF BODY WEIGHT BASED ON BODY CONDITION SCORE IN PELIBUEY EWES

Abstract

The use of body condition score (BCS), as a tool for monitoring the energy balance and body reserves of sheep, involves establishing the relationship between BCSC and body weight (BW). The objective of the study was to evaluate a prediction equation for BW of non-pregnant and non-lactating Pelibuey ewes, which was developed using a data set composed by 303 2-3-year-old, non-pregnant and non-lactating Pelibuey ewes with a mean BW of 44.71± 9.98 kg and BCS (BW= 22.47 + 6.90 * BCS). The evaluation of the equation was assessed with the Model Evaluation Systems using an independent data set of BW (37.38±7.71 kg), and BCS (2.2±1.10 units) obtained from 52 non-pregnant and non-lactating Pelibuey ewes. The linear regression analysis between BW values observed and predicted showed that the intercept did not differ from zero (0.311, P = 0.91) and the slope did not differ from one (0.984, P = 0.83). The model proved accurate, the point (0, 1) is within the ellipse; the point F was not significant (P = 0.3477). The equation presented a mean precision (R2 = 0.7924) and a good accuracy (bias correction factor, Cb = 0.99). The modeling efficiency (MEF = 0.7911) indicated a relatively high value of concordance between the observed and predicted values. The concordance correlation coefficient between both values was 0.89. The RMSEP (root mean square error prediction) accounted for 9.27% from BW observed. The predictive model presented a good precision and accuracy to estimate BW of non-pregnant and non-lactating Pelibuey ewes with PV ranges from 26.3 to 75.0 kg reared under production systems of the humid tropic. In addition, the model suggests that 6.90 ±0.32 kg of BW is required to increase BCS in one unit in this type of Pelibuey ewes.