Prediction of bodyweight from body measurements in rabbits using principal component analysis

The study aimed at describing objectively the interdependence among the biometric traits and to predict body weight from their orthogonal body shape characters using principal component factor analysis. Body weight and ten biometric variables namely body length, height at wither, thigh circumference, shoulder to tail drop, ear length, heart girth, tail length, length of front and back leg and nose to shoulder were measured on eight week old 104 F1 progeny Hyla rabbits of two genetic groups (NZWXNZW purebred and NZWXCAL crossbred rabbits). General linear model and principal component analysis procedure of statistical analysis system (S.A.S 9.0) was used to compute the variations between the two breeds. Pair wise correlations between bodyweight and biometric traits were positive and highly associated (r = 0.60-0.90, 0.62–0.94; P<0.01) for Hyla purebred and crossbred rabbits. In the factor solution of the principal component analysis, with varimax rotation of the transformation, two factors were identified for the first genetic group and three factors for the second genetic group (ratio of variance = 83.97 and 89.88% for NZWXCAL crossbred and NZWXNZW purebred rabbits respectively). The first factor in each case accounted for the greatest percentage of the total variation, and was termed general size. The subsequent factors (indices of body shape)presented patterns of variation independent of general size. Theprincipal component based regression models, which are preferablefor selecting animals for optimal balance, accounted for 88% of thevariation in the body weight for both Hyla purebred and crossbredrabbits respectively.

کلیدواژه ها:

Biometric traits ، Principal component analysis ، Multivariate analysis ، Statistical methods ،