Genetic characterization of Southern African sheep breeds using DNA markers
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Date
2006-05-16
Authors
Buduram, Pranisha
Journal Title
Journal ISSN
Volume Title
Publisher
University of the Free State
Abstract
Merino sheep are an important resource for South Afric an farmers, providing
meat and wool and thus an important income source. Indigenous and locally
developed breeds are an important asset for many reasons, but particularly because,
over time, they have developed unique combinations of adaptive traits to respond to
the pressures of the local environment. To be able to distinguish between breeds for
conservation and utilization purposes, the genetic variability, population structure and
phylogenetic relationships were determined. Seven different Merino genotypes were
sampled. These included the Dormer, SA Merino, SA Mutton Merino, Landsheep,
Letelle, Dohne and Afrino. The indigenous and locally developed breeds comprised
of the Damara, Pedi, Blinkhaar Ronderib Afrikaner, Blackhead Persian, Blackhead
Speckled Persian, Redhead Persian, Redhead Speckled Persian, Zulu, Namaqua
Afrikaner, Karakul, Swazi, Van Rooy and Dorper.
The Merino, indigenous and locally developed breeds were assessed for genetic
diversity using 24 microsatellites. Different statistical analyses were performed to
determine the genetic variation, genetic relationships and genetic differentiation of the
breeds.
The SA Merino showed a high number of very distinct alleles. This study
confirmed a higher variability of the SA Merino when compared with the other
breeds. The genetic distance between the SA Merino and SA Mutton Merino, both
fine wool breeds, was high indicating that these two breeds are relatively distant from
each other. The Afrino known to have 25% SA Merino, 25% Ronderib Afrikaner and
50% SA Mutton Merino, indicated a closer relationship with the SA Mutton Merino.
This result confirmed the development of the breed. From the phylogenetic analysis
between the seven Merino genotypes, when compared to the other estimates obtained
in the study, it was evident that the Merino genotypes in South Africa have more
within breed variation than between breed variation.
The genetic distance estimates observed for the indigenous fat-tailed breeds were
relatively high indicating that even between these breeds genetic differences exist. As
expected, a smaller genetic distance between the Persian varieties was observed.
Genetic distances between the developed breeds supported their ancestral development. The results of the indigenous and locally developed breeds present the
first study of the genetic characterization of these breeds using microsatellite markers
in South Africa.
Southern Africa is hosting a very large sheep (Merino, indigenous and locally
developed) genetic resource. Adapted to the agricultural production systems of the
continent, it represents a unique resource that has great potential for further
development of its productivity.
Description
Keywords
Dissertation (M.Sc.Agric. (Animal, Wildlife and Grassland Sciences))--University of the Free State, 2004, Sheep -- Breeding, Sheep -- Genetics, Sheep -- Reproduction