Department of Animal Science, School of Agriculture, College of Agriculture and Natural Sciences, University of Cape Coast, Cape Coast, Ghana.
Department of Molecular Biology and Biotechnology, School of Biological Sciences, College of Agriculture and Natural Sciences, University of Cape Coast, Cape Coast, Ghana.
Trop Anim Health Prod. 2021 Jan 4;53(1):69. doi: 10.1007/s11250-020-02498-x.
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 1-4 years 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 (D) 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.
一项研究旨在基于形态特征对四个西非小山羊种群进行特征描述和区分，并使用线性身体测量来预测它们的体重。总共从加纳中带和南部的四个农业生态区采集了 384 只山羊样本。使用单变量和多变量分析检查了用于表型分化的形态特征，包括体重、体长、肩高、胸围、胸深、肩宽、臀部长度、臀部宽度、头长、头宽、胫骨周长、角长、耳长、尾长和毛长。结果表明，农业生态区和年龄显著（p<0.05）影响大多数性状的表现。性状之间的表型相关性在 0.06-0.67 之间较低至高，表明这些性状之间存在线性关系，这可能是遗传和环境因素共同造成的。回归分析还表明，对于 1-4 岁的雄性西非小山羊，单一特征（可能是胸围/心围）可用于预测其体重，而对于雌性小山羊，单一特征（可能是肩高）可用于预测其体重。所有种群彼此之间均存在显著差异（p<0.0001），但在过渡区 P1 和雨林区 P3 的西非小山羊种群之间估计的最大马氏距离（D）最大（4.62），而在过渡区 P1 和半落叶林区 P2 之间最小（1.61）。在种群内个体之间发现最高的相似性是在雨林 P3（79.76%），而在过渡区 P1 中发现最低（47.13%）。三个典型成分（Can1、Can2 和 Can3）解释了形态特征的种群间总变异（100%）。然而，在方差的分配中，前两个典型成分（Can1 和 Can2）占种群间方差的累积比例为 84.35%。按照重要性顺序，尾长、头长、耳长、胫骨周长、头宽和肩宽是导致四个山羊种群变异的最具鉴别力的变量。总之，加纳的西非小山羊种群之间存在形态变异。然而，建议进一步研究这些种群的分子遗传多样性，以支持可持续的品种改良策略。此外，还制定了可以可靠地预测 WAD 山羊体重的方程，未来的研究还应集中开发仅基于胸围、肩高或体长预测方程的单一变量体重估计测量带，供农民在没有称重秤的情况下使用。
