Breeding_and_Genetics

Breeding_and_Genetics - Breeding Domesticated 10,000 12,000...

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Unformatted text preview: Breeding Domesticated 10,000 12,000 years ago Major changes have been genetic (to benefit man) Increased production can be achieved through environment but must be repeated daily, seasonally or at least annually. Whereas Genetic change tends to be permanent. From a Hairy coat to 15 lbs of Wool From one kid per year to multiple births Environmental effects on Genetics Genotype vs Phenotype Breeding Change is inevitable but progress is optional To make progress some type of mating and selection program is necessary Balance in Selection Meat Wool Milk Reproduction Carcass Merit Size Technologies such as AI (intrauterine and transcervical) Embryo Transfer and Cloning have greatly increased the rate of genetic change Breeding Individuals that perform well or poorly for a particular trait pass on a portion of that good or poor performance to their progeny DNA (deoxyribonucleic Acid) is the genetic material that controls how an animal looks and performs DNA molecules are organized into chromosomes Breeding Chromosomes present in every cell of the body Found in pairs that resemble one another in size and shape An individual has the exact same set of chromosomes (and DNA) in every cell of its body Species differ in number of chromosomes per cell Sheep have 54 chromosomes or 27 pair Goats have 60 chromosomes or 30 pair Breeding DNA in the chromosomes is organized into segments Genes Gene coding system that dictates the production of enzymes and proteins which influence Development Performance Appearance The sequence of the DNA molecules within the gene determines the structure of the enzyme or protein produced The location of a gene on a chromosome is called a locus (loci) Alleles alternating forms of the gene (due to diff in DNA) Breeding Chance - which chromosome of a pair that end up in the sperm or egg is determined purely by chance. One Allele of each gene pair 50% Sire, 50% Dam Genetic variation - 134,217,728 possible combinations Breeding The 2 Alleles of a gene pair act together to determine structure and function The Alleles may be the same or different If Alleles are the same Homozygous If Alleles are different Heterozygous for that specific gene pair Breeding Heterozygous Gene Pair One allele may express itself in total exclusion of the other allele expressed allele is Dominant Allele that is not expressed is Recessive In animal genetics, Complete dominance of one allele over another is exception rather than the rule In most cases each allele of the pair expresses itself to a certain extent Breeding Spider Syndrome due to a single allele ( s ) which is recessive to the dominant allele ( S ) for normal skeletal development Since no producer would keep a spider lamb for breeding they result from a mating of two normal appearing but heterozygous individuals Spider Gene in Sheep Breeding...
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This note was uploaded on 01/16/2012 for the course ANSCI 313 taught by Professor Dr.allanmorgan during the Fall '11 term at Tarleton.

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Breeding_and_Genetics - Breeding Domesticated 10,000 12,000...

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