Application of Morphological Indices in the Assessment of Type and Function in Sheep

The assessment of the powers of body measurements in the estimation of weights and the accuracies of body weights in the estimation of size among livestock species has been widely reported. Body weight is the commonly reported measure of size (Fitzhugh & Bradford, 1983). The reliability of single measurements such as wither height, body length, heart girth, rump height and width e.t.c. in the estimation of weight at both traditional and institutional levels have been widely documented. Others have even used cephalic dimensions as indicators of breed, origin and relationships within species (Jewel, 1963). EAAP and FAO have used wither height as a prime indicator of type in beef (Simon & Buchanauer, 1993) because it indicates long bone growth. But sometimes, rump height has been preferred to wither height. Recently, both height at withers and rump have been considered limited in their values as indicators of weight and as having negligible value as indicators of type and function. Beyond just weights type and function as a better indicator of the usefulness of the animal is fast becoming more important. Ordinarily, even the value of weight itself is limited without some qualification and probably quantification of associated type and conformation. Alderson (1999) reported that single linear measurements are more relevant for on-farm within-herd use. This is probably because of the reported significant influence of husbandry system on certain body measurements. However, different combinations of the measurements will likely be more useful.