Abstract
Sheep is an important livestock species of Tunisia. They contribute greatly to the food safety of the country and in the livelihood of a large number of small and marginal farmers and landless labourers engaged in sheep rearing. In this study, random amplified polymorphic DNA-polymerase chain reaction (RAPD-PCR) analysis was used to assess the genetic difference and gene flow among two Tunisian sheep breeds (the Barbarine and the Western thin tail). A total of 62 bands were detected with an average of 7.75 bands per primer. The unweighted pair-group method with arithmetic average (UPGMA) and principal component analysis (PCA) showed a clear differentiation between the two studied breeds. Genetic differentiation coefficient (Gst) over all loci was 0.1922, the fixation index [Fst by Analysis of molecular variance (AMOVA)] was 0.308 (P<0.001), and the gene flow value (Nm) was 1.3102. It is clear from this study that Barbarine and Western thin tail breeds are completely distinct and that they show high and significant genetic differentiation. However, the level of gene migration between them is quite high and may lead eventually to the loss of breed’s purity. Key words: Sheep, genetic differentiation, gene flow, RAPD-PCR
Highlights
In Tunisia, there are three important livestock species: Sheep, goats and cattle which represent 77, 14.9 and 8.1%, respectively of the farm animals effective (Rekik et al, 2005)
Tunisian flock consists of four breed, mainly the Barbarine (B) (60.3%) and the Western thin tail (W) (34.6%) which are reared across all the territory, and the Black of thibar (2.1%)
The number of fragments detected by each primer varied from six for OPA06 and OPA12 to 11 for the OPA10 (Table 1), with a mean of 7.75 fragments Elmaci et al (2007) reported that the number of fragments revealed by each primer varied from three to 14 in Turkish sheep breeds
Summary
In Tunisia, there are three important livestock species: Sheep, goats and cattle which represent 77, 14.9 and 8.1%, respectively of the farm animals effective (Rekik et al, 2005). With a population of over four million female sheep, domestic sheep (Ovis aries) species has an important economic role in Tunisia. It constitutes the main source of meat and provides more than 41% of the country’s total red meat production. Tunisian flock consists of four breed, mainly the Barbarine (B) (60.3%) and the Western thin tail (W) (34.6%) which are reared across all the territory, and the Black of thibar (2.1%). Bedhiaf-Romdhani et al (2008) reported that farmers are crossing the local Barbarin with thin tailed breeds (W and Black of Thibar) due to the difficulty of selling the fat of the tail that represents up to 15% of the carcass weight in the B breed. Intermixing of breeds may pose a danger of maintaining breed purity in
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