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Cambridge sheep

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The Cambridge is a composite breed developed from a set of 54 ewes with exceptional prolificacy selected in Britain in 1964.  The foundation ewes had to have achieved a minimum prolificacy of three sets of triplets in consecutive lambings (Owen 1982).  The ewes selected were mostly purebred; 34 were from the Clun Forest breed while the remainder represented 10 other British breeds. The foundation ewes were mated by Finnish Landrace rams in the first year of the programme while the selected males from these mating ewes used in the following year.  The flock was closed at this stage and the Cambridge breed was developed through selection for prolificacy and milk production (50-day litter weight).  The contribution of the Finnish Landrace to the ancestry of the modern Cambridge was stated to be about 20% (Owen et al. 1986).  A study of ovulation rate in the breed revealed a degree of variation (1 to 14; Hanrahan and Owen, 1985) that was consistent with the segregation of a gene(s) with a large effect(s) on ovarian function.  This hypothesis was confirmed by the identification of point mutations in the genes coding for BMP15 and GDF9 (Hanrahan et al. 2004) that had large effects on ovulation rate in heterozygous carriers; homozygous carriers were sterile due to ovarian hypoplasia.  However, these mutations did not explain all of the variation seen in ovarian function and subsequent data led to the hypothesis that an autosomal recessive gene was segregating that caused ovarian hypoplasia (Hanrahan 2009).  This gene may also be associated with canalisation of ovulation rate in heterozygous carriers.

For the purposes of the present project, a population of approximately 60 animals managed by 3SR partner Teagasc will be used in QTL discovery and validation. Whole-genome genotypes will be based on an analysis with the 50K SNP array. Phenotypes will pertain to ovulation rate.



 



References

Owen JB. 1982. 33rd Meeting EAAP, Leningrad, 7p.

Hanrahan JP and Owen JB 1985. BSAP Winter Meeting, paper 37.

Owen, JB et al. 1986. Animal Production 42:355-364

Hanrahan JP et al. 2004. Biology of Reproduction 70:900-909.

Hanrahan JP. 2009. Proc. BSAS p 42.

 

 
  This website represents the views of the Authors, not the EC. The EC is not liable for any use that may be made of the information contained herein. 3SR is a Collaborative Project funded under the 7th Framework Programme (FP7).