Abstract:
The aim of this study was to characterize indigenous Tswana goats in four agro-ecological regions of
Botswana i.e. Southern, Central, Northwest and Ghanzi. The following specific objectives were set;
description of existing goat production systems in Botswana, phenotypic and genetic characterisation
of Tswana goats and investigation of population structure of indigenous and commercial goats using
the Goat50K SNP panel. A survey was conducted in four agro-ecological regions to collect data on
Tswana goats in smallholder farming systems and phenotypic measurements were recorded for 123
goats that included body weight (BW), body length (BL), heart girth (HG), height at withers (HW)
and tail length (TL). Qualitative traits such as coat colour, horns and beard were also recorded. About
80% of the farmers kept goats for financial purposes. Goats in the Northwest region had significantly
(P<0.05) higher HG values in all age groups compared to other regions. Goats in the Central
(71.83±1.18) and Northwest (69.17±2.04) regions had significantly longer BL compared to the ones
in the Southern (64.25±2.50) region at >48 months. For genetic characterisation, hair samples from 48
phenotyped animals of Central region were collected and genotyped with Illumina Goat50K SNP
chip. Genomic diversity was high (0.423±0.03) with low inbreeding (FIS) (0.009±0.05). Additional
genotypes which included Boer (n=24), Kalahari Red (n = 24) and Swazi (n=48) were included in the
analysis to get a broader regional perspective. Genetic diversity, measured as expected heterozygosity
was 0.390±0.01, 0.398±0.01 and 0.387±0.02 for Boer, Kalahari Red and Swazi goats, respectively.
Inbreeding coefficient ranged from 0.014±0.06 in Boer, 0.012±0.07 in Kalahari Red to 0.011 ± 0.06 in
Swazi goats. The populations clustered according to geographical origin. Linkage disequilibrium (LD)
for shorter intervals (0-10 kb) ranged from 0.44 to 0.56. Effective population size at 13th generation
was approximately 87 for Boer, 93 for Kalahari Red, 180 for Swazi and 266 for Tswana goats. The
results indicate potential improvement of Tswana goat through within breed selection and structured
crossbreeding that will assist in food security and sustainable utilization.
