Principal component analysis of the conformation traits of Yankasa sheep

Abstract

This study was preformed to evaluate the biometric traits of 227 Yankasa sheep in northern Nigeria under a multivariate approach. The body measurements taken were: withers height, rump height, body length, heart girth, tail length, face length, shoulder width, head width, rump width, ear length, foreleg length, hind leg length and rump length. The animals were divided into two age groups: <15.5 and 15.5 - 28.3 months old, respectively. General linear model was used to study age group effect while principal component factor analysis was performed to define body shape upon the correlation matrix of the thirteen body measurements. Age group significantly (P<0.05) affected the morphological characters except ear length. Pearson?s coefficients of correlation were positive and significant in both age groups. In <15.5 months old sheep, four principal components (factors) were extracted (ratio of variance = 89.27). The first factor accounted for 73.03% of the total variance and was interpreted as a measure of general size. The second factor which explained 7.61% of the generalized variance tended to describe flesh dimensions (shoulder width and rump width), while the third factor had its loadings for tail length and ear length. The fourth factor was influenced by head width. In 15.5-28.3 months old sheep, three factors (ratio of variance=75.21) were identified. These seven extracted factors could be considered in breeding programmes to improve body conformation of sheep since variation in meat traits was not associated with body height.