Morphometric characterization and differentiation of West African Dwarf goat populations in Ghana.

Abstract

A study was carried out to characterize and differentiate four West African Dwarf goat populations on the basis of morphometric traits and also predict their body weights using linear body measurements. A total of 384 goats were sampled from four agro-ecological zones from the middle belt and southern part of Ghana. The morphometric traits examined for phenotypic differentiation using univariate and multivariate analysis were body weight, body length, withers height, chest girth, chest depth, shoulder point width, rump length, rump width, head length, head width, shin circumference, horn length, ear length, tail length, and hair length. Results obtained showed that agro-ecological zone and age significantly (p < 0.05) influenced the performance of most traits. The phenotypic correlations among the traits were low to high (0.06-0.67) indicating linear relationships among these traits which may be caused by both genetic and environmental factors. The regression analysis also revealed that a single trait which may be used to predict the body weight of male West African Dwarf goats of ages 1-4years is chest/heart girth and that of female counterparts is withers height. All the populations were significantly (p < 0.0001) distant (differentiated) from each other, but the largest (4.62) estimated Mahalanobis distance (D2) was between West African Dwarf goat populations in the transitional zone P1 and the rainforest P3 while the least (1.61) was observed between transitional zone P1 and semi-deciduous forest zone P2. The highest similarity between individuals within population was found in the rainforest P3 (79.76%) and the lowest in the transitional zone P1 (47.13%). The three canonical components (Can1, Can2, and Can3) explained the total (100%) between-population variation in morphometric traits. However, in partitioning of the variance, the first two canonical components (Can1 and Can2) accounted for cumulative proportion of 84.35% of between-population variance. In order of importance, tail length, head length, ear length, shin circumference, head width, and shoulder point width were the most discriminating variables responsible for the variations among the four goat populations. In conclusion, morphometric variations exist among West African Dwarf goat populations of Ghana. Yet, further studies on molecular genetic diversity of the populations are recommended to support a sustainable breed improvement strategy. Also, equations have been developed that can be used to reliably predict the body weight of WAD goats and future research should also focus on developing single variable weight estimator measuring tapes based only on either the chest girth, withers height, or body length prediction equations for farmers to use in the absence of weighing scale.