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Course: Animal Breeding

Course: Animal Breeding. Instructor: Dr. Jihad Abdallah New approaches in Animal Breeding. Gene detection and Gene mapping. Use of DNA marker information to locate important genes on the chromosomes: Major genes: genes which have large effect on the given trait

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Course: Animal Breeding

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  1. Course: Animal Breeding Instructor: Dr. Jihad Abdallah New approaches in Animal Breeding

  2. Gene detection and Gene mapping • Use of DNA marker information to locate important genes on the chromosomes: • Major genes: genes which have large effect on the given trait • QTL (Quantitative Trait Loci): having small or intermediate effects on quantitative traits. • Examples of major genes: - Booroola gene (fecundity gene) - Double muscling gene in cattle (Charolais, Belgium blue) – on chromosome number 2. - Callipyge gene in sheep (near the telomere region of chromosome 18 )

  3. Double muscling in Cattle Callipyge sheep

  4. Methods used in gene detection and mapping • Linkage Analysis: consists of following the segregation of marker alleles in known family pedigrees. • Linkage disequilibrium analysis: used in outbred populations (unrelated individuals). Linkage disequilibrium measures the association between alleles on different genes.

  5. Marker Assisted Selection • The use of information on markers close to detected genes to assist in prediction of breeding values of animals  use of marker information + phenotypic information. • Increases accuracy of selection: provides more information particularly on young animals which have no records.

  6. Genomic Selection • Use of information on a large number of DNA markers to predict the breeding value of the animal without using phenotypic records. • Advantage: can be used on very young animals resulting in decreased generation interval. • If we can achieve the same accuracy of selection as with using phenotypic records (as in progeny tests)  genetic change per year is greatly increased.

  7. Animal Cloning • Production of genetically identical animals. • Dolly was the first animal to be cloned via nuclear transfer from a cultured somatic cell derived from an adult. • This process, known as SCNT (somatic cell nuclear transfer) cloning. • This allowed cloning technology to be extended to make copies of top breeding animals with well established breeding superiority based on their own performance records, and those of their offspring.

  8. Transgenic Animals • Transgenic animal is an animal to which a gene has been transferred (inserted) from another organism. • Once scientists have identified and isolated the piece of DNA comprising the gene to be transferred, it is injected into a fertilized egg of the desired animal using a very small glass needle visualized under a microscope. • In approximately one percent of the cases, the gene becomes incorporated into the genome of the egg. • Ideally, the new gene integrates into the genome before the egg begins to divide. If this occurs, every cell in the animal contains the new gene animal will pass the gene on to its offspring.

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