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Molecular genetics of sex determination and gonadal development in birds - LS3301

In the UK, there are major inefficiencies in reproductive performance of the layer and broiler poultry industry which result in large numbers of birds of unwanted sex which are either killed or reared uneconomically. The consequences are a higher than necessary environmental pollution and difficult to resolve welfare issues.
The production of male and female chicks in equal numbers is a major constraint on the poultry industry. Layer strain chicks have to be sexed on day of hatch and the unwanted males killed. Poultry meat producers would prefer all male birds due to their faster growth rate and better food conversion but currently have to accept the relative inefficiency of an equal number of slower growing females. As a consequence, an ability to manipulate sex ratios to produce all female layers and all male meat birds would have very substantial economic and welfare benefits for the poultry industry.
Limited sex reversal has already been achieved in chickens by administering steroids or interfering with steroid synthesis. However, these attempts were unsuccessful from a commercial standpoint as the sex reversed females (i.e. phenotypic males) did not exhibit the normal male growth characteristics. Attempts to manipulate sex ratios by early sex identification have also proved impractical due to the high degree of technical expertise required. Avian molecular sexing assays developed to date have relied on either nucleic acid hybridisation to, or PCR amplification of, sex chromosome sequences.
We believe that successful manipulation of sex ratios in birds will only follow a much better understanding of the processes controlling sex determination and gonadal development in early embryogenesis. In recent years, we and others have made major advances in our understanding of these developmental process.
The overall objective of our work is to elucidate the mechanism of sex determination in birds so as to devise strategies to manipulate sex ratios. We will follow three separate approaches; analysis of individuals with sex chromosome anomalies, characterisation of candidate sex determining/identifying genes, and the development and optimisation of a simple sexing test.
In addition to providing a basic understanding which should permit us to devise efficient methods of altering sex ratios, we expect the results to provide simple methods for sex identification in ovo.

Project Documents
• Final Report : Molecular genetics of sex determination and gonadal development in birds   (49k)
Time-Scale and Cost
From: 2000

To: 2003

Cost: £432,950
Contractor / Funded Organisations
Roslin Institute, Edinburgh (BBSRC)
Livestock Farming              
Fields of Study