Fixing multicollinearity in modelling market body weight of Sudani ducks (Cairina moschata) from early age morphometric traits

A.O. Oguntunji1*, A. Makram2

1Department of Animal Science and Fisheries Management, Bowen University, P.M.B. 284, Iwo, Osun State, Nigeria 2Department of Poultry Production, Faculty of Agriculture, Ain Shams University, Cairo, Egypt

(Manuscript received 5 September 2019; accepted for publication 31 October 2019)

Abstract: Morphometric parameters and their indices are central to characterization, selection and genetic improvement of farm animals. The present study was conducted to fix multicollinearity among predictors and to fit optimum regression model for prediction of 14-week body weight of 150 un-sexed Sudani ducks from early age (0, 2, 4 and 6 weeks of age) morphometric measurements (body weight, body length, breast circumference and keel length). Pairwise correlation between the 14-week body weight (BWT) and measured variables was the highest with 2-week BWT (r=0.934, P<0.001). Application of multicollinearity diagnostics (variance inflation factor, tolerance, eigenvalues and condition index) revealed collinearity among six variables. Stepwise regression equation identified 2-week BWT as the most important predictor accounting for 87.30% of the total variation of the response variable. However, the optimum regression model for prediction of adult body weight was fitted with 2-week BWT in quadratic model having the highest predictive power (Coefficient of determination /R2/=0.966 and least root mean square error /RMSE/=4.269). This result is applicable under field conditions for both researchers and duck farmers for early selection of 14-week market body weight of Sudani ducks at 2 weeks of age.