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Genetic Variation on the Control or Resistance to Infectious Diseases in Small Ruminants for Improving Animal Productivity (D31026)

This CRP has been successful in bringing together researchers from 16 different institutions for collaboration on the characterization of sheep and goats for their resistance to gastrointestinal (GI) parasites. The chemical control of GI parasites is not only expensive but also it leaves drug residues in food and environment with serious impacts on public health. Identification of genetic markers in sheep and goats for marker-assisted breeding to develop an animal population naturally resistant to parasites will be very important step forward to the sustainable livestock industry for global food security. The molecular techniques developed and capacity strengthened in Member States (MS) for genome analysis can also be used to investigate genetic variations and associations to resistance/susceptibility to other infectious diseases and animals’ ability to thrive on poor quality feed and in harsh environmental conditions.

Some of these sheep are more resistant to parasite infections than other. Molecular genetics helps identify the resistent animals as beeding stocks.

Two major research trials (i.e. artificial challenge and field trial) were designed for sample and data collection during the first RCM (Vienna, 21–25 February 2011). The artificial challenge trial in the first phase of CRP was conducted to assess the genetic potential of local sheep and goat breeds for parasite resistance. The field trial being implemented in the second phase of the CRP focusses on recording phenotypic data and field testing of DNA markers related to parasite resistance.
All Research Contract Holders (RCHs) have completed the artificial challenge trial and presented the data during the second RCM held in Bogor, Indonesia (11–15 February 2013). Based on preliminary results, there are clear indications of potential for genetic resistance against parasites in local sheep and goat breeds. For example, the research team in Argentina has already initiated a breeding programme where rams are being selected for parasite resistance. Nigeria was successful in establishing a goat tribe to implement breeding program to improve parasite resistance in local breeds. In addition to the research trials, a Radiation Hybrid panel for goats (Capra hircus) was developed as a resource for rapid and large-scale physical mapping of the goat genome. The goat radiation hybrid panel helped Chinese researchers to assemble the first ever draft genome sequence of domestic goat published in 2013 http://www.nature.com/nbt/journal/v31/n2/full/nbt.2478.html. The goat radiation hybrid map is also used in evaluating candidate genes for identification of DNA based markers associated with infectious disease resistance and develop analytical tools for marker assisted breeding.

Goats vary in their capacity to thrive on poor forages and harsh environment and resistance to infections. Identification of appropriate genetics and their incorporation in breeding keys to the sustainable development of goat farming.

RCHs have already started or nearly completed the field trial that involves recording phenotypes in sheep and goat breeds for resistance to natural infections with parasites. DNA has been extracted from blood samples and most of the RCHs have sent an aliquot to the IAEA’s Animal Production and Health Laboratory (APHL) in Seibersdorf for genotyping. APHL has discovered 181 Single Nucleotide Polymorphism (SNP) based DNA markers in sheep and 170 in goats across different candidate genes involved in disease resistance pathways. These DNA markers are currently under field testing in about 3000 sheep and 1500 goats located in different participating member states. RCHs in the CRP were successful in collaborating with other institutes and have also used additional IAEA support under national and regional TC projects for training their personnel in DNA based technologies for genetic improvement of sheep and goats.

This CRP has been highly appreciated by MSs. 16 research institutions from following member states are participating in this project: Argentina, Bangladesh, Brazil, Burkina Faso, China, Ethiopia, Indonesia, Islamic Republic of Iran, Italy, Kenya, Nigeria, Pakistan, Saudi Arabia, Sri Lanka and USA. Eight Arab-Asian MSs are involved in a regional Technical Cooperation (TC) project for building capacities on genetic characterisation of small ruminants (Iraq, Jordan, Lebanon, Oman, Qatar, Saudi Arabia, Syrian Arab Republic, Yemen). Four 4 MSs are being now assisted by IAEA through national TC projects to characterise their indigenous animal species. The CRP will end in 2015.

Genetic structure of sheep breeds based on genetic variations in candidate genes related to disease resistance