Domestication in livestock industries is the process in which animal populations change in response to the artificial environments of farming production systems. Genetic changes within the populations give rise to physiological and behavioural changes which enable the domesticated stocks to perform better within the farming environments. Genetic improvement within livestock breeding programs occurs through targeted selections of traits of economic value based on knowledge of the underlying genetic architecture of these traits. Genetic improvement also occurs through indirect selections for the diversity of traits that allow the populations to survive and reproduce within these artificial environments (this has been referred to as 'domestication selection').
Significant and widespread economic gains have been achieved through genetic improvements made through domestication and selective breeding of commercially farmed shrimp species, particularly Litopenaeus vannamei. The long-term economic benefits of shrimp breeding programs has depended on the degree to which a sound understanding of quantitative genetics has been applied within these programs, coupled with the surety in the captive propagation of specific genotypes within the programs. The economic benefit of these programs has also depended on the success of implemented approaches to health management. Many shrimp programs and industries have relied on using specific pathogen free (SPF) stocks due to the devastating impacts of several highly pathogenic viruses, coupled with the constraints to genetic improvement through reported low heritabilities for disease-resistance traits and unfavourable genetic correlations between disease-resistance and growth traits. This preference for pathogen exclusion has commonly seen genetically-improved stocks developed irrelative to viral-resistance.
Different governmental policies on the translocation of shrimp genetic resources have influenced the approaches taken toward shrimp domestication and breeding in different countries. The challenge of domesticating locally availing shrimp species has influenced decisions by many governments to allow imports of foreign domesticated species and stocks. Despite the significant economic gains achieved in many regions through the use of exotic lines, the widespread translocation of domesticated stocks, often of unknown genetic and health background, does pose risk to local industries, other industry sectors and local native species. The reliance on domesticated stocks developed irrelative to the endemic pathogens that present within the local environment also poses risks to the local farming industries.
The present paper examines the different approaches to domestication and genetic improvement employed in shrimp breeding. Alternative approaches for future domestication, genetic and health management of developing breeding programs are discussed, particularly given recent widespread stock losses throughout Asia. Opportunities to employ new technologies and approaches for establishing new lines, in managing health within the programs, and for mitigating risks associated with translocation of domesticated stocks and genetic resources is discussed. Particular reference is made to experiences with the domestication and breeding of Penaeus monodon in Australia.
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