Principal component analysis of carcass traits in commercial broilers

Data on body weight, dressed weight, weight of wings, thighs, drumstick, breast, liver, gizzard, heart, proventriculus, and abdominal fat were recorded on commercial broilers. Two batches of broiler chicks were reared under same management conditions and forty birds from each batch were slaughtered at six weeks of age. Male broilers had significantly higher weights than females with respect to all traits except gizzard, proventriculus and abdominal fat. The data was corrected for sex and batches by GLM- Least square correction. The correlations among the variables showed that live body weight, weights of dressed chicken, drumstick, wings and thigh are high and positively correlated. The correlation values obtained were in the range from 0.59 to 0.96. Moderate to high and positive correlation values ranging from 0.31 to 0.53 were observed between live body weight and weights of heart, liver, gizzard and proventriculus. Weight of abdominal fat showed no significant correlation with the rest of the variables, clearly distinguishing the variables into three groups. The data was checked for normality. Variable gizzard was square root transferred to attain normality. Principal Component Analysis by correlation and varimax rotation method identified four factors with 86.23 per cent of total variation. First factor accounted for 53.58 per cent of the generalized variance and had its loading for body weight, dressed weight, weight of wings, thighs, drum stick, and breast. Second factor with 14.70 per cent had its loading for weight of abdominal fat. Third factor with 9.68 per cent had loading for weight of heart, liver and proventriculus and fourth factor with 8.25% had loading for weight of gizzard.