Principal component analyses of Awassi sheep in Iraq

How to Cite

Principal component analyses of Awassi sheep in Iraq. (1977). Tropical Agriculture, 54(3).


Body weight and six skeletal dimensions of 108 male and 116 female Awassi lambs were recorded at weaning. Two principal component analyses, one for each x, were undertaken. The principal component technique provides a method of explaining the covariance structure among a large system of measurements by generating a smaller number of artificial variates which contrast animals of different sizes and shapes. The first component was found to be useful in ranking lambs on general size. This component accounted for 63 and 54 per cent of the total variation in male and female data, respectively, and provided a linear function of size with nearly equal emphasis on all seven standardized traits. The second principal component indicated that two basic extreme in body shape apparently exist among all lamb and that it is useful in ranking animals between these extremes. In general, the second component for each sex contrasted wide lamb with short and hallow bodied lambs. The third component added little information and contrasted tall lambs with short bodied lambs. It appears that performance testing programmes should include measures of body size (principal component indices) in addition to weight and age if potential sires are to be accurately evaluated. These indices would be very handy in electing replacement lambs at weaning age.