Animal Genetics

The body is made up of millions of tiny cells The contents of the cell is called protoplasm. Animal cells are the smallest living things in the world. Animals are made purely of cells.

Animal Genetics The Cell Components Nucleus Gives cells the ability to grow, to digest food and to divide, contains chromosomes composed of genes. Cytoplasm Gives the cell shape and contains components necessary for cell functions.

Animal Genetics The Cell Components Cell Membrane Outside of the cell, allows only certain materials to pass in and out of the cell.

Animal Genetics Nucleus Cytoplasm Cell Membrane

Animal Genetics Cell Division Mitosis Increases total number of cells Results in animal growth Chromosomes pairs are duplicated

Animal Genetics Cell Division Meiosis Produces gametes Only have one-half the chromosomes of normal cells

Animal Genetics Chromosomes Rod shaped bodies Made of proteins Found in the nucleus of the cell Exist in pairs Except in gamete cells (single chromosome)

Animal Genetics Chromosomes The number of chromosome pairs differs for various animals COW30HORSE33 PIG19 CHICKEN6 HUMAN23

Animal Genetics Genes Located on chromosomes Thousands found in each animal Inherited from parents Control inherited characteristics Carcass traits Growth rate Feed efficiency

Animal Genetics Genes Two types of inherited traits DominantRecessive Gene combinations HeterozygousHomozygous

Animal Genetics Genes Dominant gene Hides the effect of another gene Polled condition in cattle is dominant The gene is represented by a capital letter Dominant Gene

Animal Genetics Genes Recessive gene Gene that is hidden by another The gene is represented by a lower case letter Recessive Gene

Animal Genetics Examples of Dominant and Recessive Genes The dominant gene is written- P The recessive gene is written-p P= Polled p= horned

Animal Genetics Gene Combinations Homozygous gene pair Carries two genes for a trait Polled cow might carry the gene PP Heterozygous gene pair Carries two different genes that affect a trait Polled cows might carry a recessive gene with the dominant Pp

Animal Genetics Predicting Genetics Genotype Kind of gene pairs possessed Phenotype The physical appearance of an animal Punnett squares Are used to predict genotypes and phenotypes of animals

Animal Genetics Predicting the Polled Trait Using the Punnett Square PP PPP P Polled Dam Polled Sire Both parents are dominant homozygous for the polled trait All offspring will be dominant homozygous for the polled trait

Animal Genetics Predicting Dwarfism Using the Punnett Square NN NNN nNn Normal Dam Carrier Sire A homozygous parent crossed with a heterozygous parent Two offspring will be homozygous for the normal trait and two offspring will be heterozygous (carriers of dwarfism)

Animal Genetics Predicting Coat Color Using the Punnett Square Bb BBBBb b bb BW Dam (carrier) BW Sire (carrier) Both parents are heterozygous (carriers for the recessive coat color) One offspring will be homozygous dominant, two will be heterozygous, and one offspring will be homozygous recessive The normal coat color of Holstein cows is black and white (BW) the recessive color is red and white (RW)

Animal Genetics Predicting Coat Color Using the Punnett Square Bb bBbbb bBbbb BW Dam (carrier) RW Sire A heterozygous parent (carrier) crossed with a recessive homozygous parent Two offspring will be heterozygous (carriers) and two offspring will be homozygous recessive The normal coat color of Holstein cows is black and white (BW) the recessive color is red and white (RW)

Animal Genetics Writing Genotypes and Phenotypes Using the Punnett Square Bb bBbbb bBbbb BW Dam (carrier) RW Sire The normal coat color of Holstein cows is black and white (BW) the recessive color is red and white (RW) Genotypes Bb and bbBb and bbPhenotypes Black and White CoatBlack and White Coat Red and White CoatRed and White Coat

Animal Genetics Heritability Estimates the likelihood of a trait being passed on from the parent to the offspring Low heritability Slow herd improvement High heritability Faster herd improvement

Animal Genetics Heritability Heritability for carcass traits are higher than reproductive traits Low heritability is improved most through environment High heritability is improved most through selective breeding and environment Estimates vary from 0 to 70% Swine rates are usually lower than cattle

Animal Genetics Heritability Estimates Fertility 10% Birth Weight 40% Weaning Weight 25-30% Yearling Weight 60% Tenderness 60%