Introgressing a Gene Mutation for More Prolific Fat-tailed Ewes in Tunisia

• Mourad Rekik - Principal Scientist - Small Ruminant Physiology and management  
• Aynalem Haile - Principal Scientist - Small Ruminant Breeder  
• Tesfaye Getachew Mengistu - Research Management Coordinator 

ICARDA scientists and partners INRAT help Tunisian family farmers increase prolificacy rates of fat-tailed ewes for better incomes. 

There are about 6.5 million sheep in Tunisia, playing an essential role as valuable assets in the livelihoods of resource-poor farmers, by providing them with financial security. Sheep offers a wide range of products such as meat, milk, and wool, for selling at the market or use within the household. 

Of the common sheep breeds in the country, the Barbarine fat-tailed sheep is the most important due to a number of factors. Beyond its cultural roots in Libya, Algeria, and Tunisia that stem to the steppes of the fertile crescent, It boasts a hardy constitution, highly advantageous in the face of climate change, characterized by metabolic and digestive adaptation to the contrasting environmental conditions prevailing in the country (heat stress, water deprivation, salinity, etc.). The sheep also possesses a fat tail that can sustain it when food is scarce.  The breed has the reputation to maintain satisfactory reproductive performance even under challenging environmental conditions and is known for its low prolificacy and most females give birth to single litters. A prolificacy-based selection program that screens herds of the Barbarine breed for prolific ewes was launched in 1979 by the Tunisian National Institute for Agronomic Research (INRAT) in the experimental center of Oueslatia (Kairouan) and succeeded in identifying a prolific strain with an average litter size of 1.6. To take further advantage of this "W-INRAT" prolific line, INRA Tunisia, INRA France, ICARDA, and the CGIAR Research Program (CRP) Livestock, joined efforts by applying a science and technology approach and demonstrated that the increased lamb production was shown to be the resultant of novel gene polymorphism in the BMP15 gene. Introgression of such a valuable mutation to improve fecundity in Tunisian Barbarine sheep is a reasonable breeding objective in favorable environments and would help farmers living under harsh conditions improve their livelihoods by breeding in ewes with a higher prolificacy rate.

The project then facilitated the introgression of the mutation into conventional non-prolific Barbarine sheep flocks in the framework of a well-designed breeding scheme, with the aim of widely improving numbers of offspring per farm, through more prolific ewes. Centers for better access to prolific rams were also launched, and best practices for successful mating were researched and disseminated.

The project is also supported by Tunisia’s “Livestock Development and Pasture Improvement National Program” (OEP, Ministry of Agriculture) to support the delivery of the improved sires through cervical artificial insemination, data recording, and selection of animals in conventional flocks, to conserve the genetic integrity of the Barbarine breed and improve its productivity within a market-oriented framework. 

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IMPACT 
 

• In the field and at a large scale level, it is anticipated that the mutation causes an increase of 0.7 and 0.3 of ovulation rate and lambs born, respectively. 
  
   
• In its third (scaling) stage, the breeding scheme will disseminate carrier rams among 32,000 females in commercial farms.  
  
   
• Office de l’Elevage et des Pâturages (OEP) which is the main institution in the country for the development of livestock and pastures has taken up implementation of the breeding scheme and is now in charge of identifying the recipient commercial flocks, organizing the mating plans, and collecting data.