Phenotypic variation among four populations of small East African goats of Tanzania
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Date
2016-09
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Abstract
A study was carried out to assess the variation in morphological characteristics of four strains (namely, Pare, Gogo,
Sukuma and Sonjo) of Small East African (SEA) goat breed in four regions of Tanzania as a first step towards their
characterization. A total of 349 mature animals (85 to 92 animals per strain) were randomly sampled from 120
households located in the four regions. For each external qualitative traits (coat color and pattern, hair type and size,
presence of wattles and beards, horn size, shape and orientation, ear size and orientation and facial and back
profiles) and quantitative traits (body weight, heart girth, height at wither, body length, chest depth, rump height, ear
length and horn length) were recorded. Discriminant, cluster and principal component analyses were used to classify
the four SEA strains based on morphometric traits. Results for body measurements show that Pare goats had the
largest body weight (29.8 ± 0.50 kg), heart girth (72.3 ± 0.51 cm), height at wither (61.4 ± 0.43 cm), body length
(53.9 ± 0.51) and rump height (63.4 ± 0.60 cm) , followed by Gogo goats whereas Sukuma and Sonjo goats were the
smallest and lightest. Sexual dimorphism was evident for all the body measurements with males being bigger and
heavier than females in all populations. Correlations among morphometric variables were significant for most of the
pairs of variables tested, the strongest being between body weight and heart girth (r = 0.70), rump height and wither
height (r = 0.60) and body weight and chest depth (r = 0.51). Pare (39.6%) and Gogo (40.2%) were predominantly
white coloured while Sonjo were red coloured (85.4%) and Sukuma had black and white colour (66.7%). Almost all
goats were horned and did not have wattles and the majority of them had medium sized and horizontally oriented
ears. Chest depth and body weight were the most powerful discriminating traits in separating the four goat strains.
The squared mahalanobis distance based on morphological traits was largest between Pare and Sukuma goats (5.45)
and smallest between Pare and Gogo goats (0.94). Cluster analysis revealed two separate groups; a group for Pare
goats and another group comprised Gogo, Sonjo and Sukuma goats. A test for assignment of individual animals to
their respective strain showed that most Sonjo (75.3%), Sukuma (70.5%) and Pare (67.9%) goats were assigned to
their source populations while most of the Gogo goats (51.1%) were mis-assigned to other populations. It is
concluded that the four strains of SEA goat breed are heterogeneous populations with large variability in
morphological features and they could best be differentiated by chest depth, body weight and coat colour.
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Keywords
Qualitative traits, Body measurements