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ANSC 1011 Section 1 Weeks 4 + 5 Notes

by: Kristy Trahan

ANSC 1011 Section 1 Weeks 4 + 5 Notes ANSC 1011

Marketplace > Louisiana State University > Animal Science > ANSC 1011 > ANSC 1011 Section 1 Weeks 4 5 Notes
Kristy Trahan

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7. Male Reproduction 8. Genetics 9. Animal Breeding 10. Transgenic Animals Textbook/ Lecture Notes Email me at for further questions!
Introduction to Animal Science
T. Bidner
Class Notes
IntroductiontoAnimalSciences, ANSC1011, ThomasBidner
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This 14 page Class Notes was uploaded by Kristy Trahan on Sunday September 25, 2016. The Class Notes belongs to ANSC 1011 at Louisiana State University taught by T. Bidner in Fall 2016. Since its upload, it has received 17 views. For similar materials see Introduction to Animal Science in Animal Science at Louisiana State University.

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Date Created: 09/25/16
ANSC1011 Kristy Trahan Male Reproductive System  Testis- hang in the scrotum o Primary sexual organ  Hang low for temperature control  Spermatogenesis can only occur o Where the sperm and testosterone (predominant sex steroid) are made o Makes sperm everyday whether they need it or not o Technically, the bigger the better- produce more sperm o Testicular Parenchyma  Seminiferous tubules are stored here and make the sperm  Germ cells first go through meiosis and the last is mitosis, right before connecting to the sperm  Sertoli cells (nurse cells) build the seminiferous tubules- are the equivalent of the follicular cell  Surround the germ cells and provide nourishment  Space between the seminiferous tubules are the interstitium  Contain capillary beds to vascularize the seminiferous tubules o Mediastinum  The big collecting duct in the middle of the testis  Spermatic Chord o Vascular, lymphatic, and nerves o Heat exchanger o Houses cremaster muscle o Pampiniform Plexus- combination of the arteries and veins  Counter current exchange  Arteries are completely encircled by the veins  39 C- 34 C  Cools the blood going in  70 ng T/ml- 4.8 ng T/ml  Epididymis (in the scrotum with the testis) o Sperm enter through one microscopic tubule into the head, to the body, and the tail of the epididymis  Gets bigger towards the tail ANSC1011 Kristy Trahan o Is important because when the sperm come out the tail of the epididymis, they gain the ability to become mobile (progressively motile- not quite fully motile) and mature  Before, they are in a sort of suspended animation before becoming full sperm  After they reach the tail, they are fully functional and this is where you would collect sperm from if you were to use a needle and extract it o Connects to the vas deferens, then goes to the ampulla  Ampulla- holds a lot of sperm for storage and is an extension of the vas deferens  Sperm don’t mind body temperature- it’s just when they aren’t fully developed that they are really affected o Goes through the inguinal canal- hole (literally a hole) through which the veins, arteries, and spermatic chord go through  The ampulla then connects to the urethra o Sphincters that control the bladder and ejaculation control one of the two functions at a time  You don’t get urine in the semen, which would kill the sperm  They close off to either the ampulla or the bladder, depending on the action ANSC1011 Kristy Trahan  Accessory sex Glands: provide the medium to help push out the sperm when the animal ejaculates o These fluids help make up semen o Seminal Vesicles o Prostate o Bulbourethral Gland (Cowper’s)  Sigmoid Plexure o When the animals get an erection, it pushes the penis out  Doesn’t usually make it bigger o The stallion doesn’t have the sigmoid plexure- have more erectile tissue  Engorges full of blood  Castration and Cryptorchidism o Castration to remove the weak from the genetic pool, so they are easier to deal with, and to remove the stink (musk smell) o Routine castration of males not used for breeding:  Lambs- 1-2 weeks old  Boars- few weeks old  Calves- 4-6 months old  Colts- 1 year or later o Cryptorchid (crypt= hidden + orchid= testis)  May be mono (one) or bilateral (both)  The testis down still makes sperm and the other does not, but both continue to make testosterone  Testis in abdomen or inguinal cavity  Normal sexual behavior, bilateral is sterile  Heritable  Breed associations won’t let you register cryptorchid animals  Smaller animals tend to have a larger concentration of sperm in their semen  Bigger animals tend to give off a larger volume of sperm  The stallion makes a very viscous sperm (like runny jello) and the boar makes a kind of clumpy fluid  Semen collection and Evaluation o Collection via artificial vagina (boars, rams, bulls, stallions) o Collection via electro-ejaculation (bulls, rams)  Device inserted into rectum and sends an electro current  Stimulates the reproductive parts right under the rectum ANSC1011 Kristy Trahan  Ampulla, nerves, etc. o Collection via gloved hand technique (boars) o Evaluate for volume, concentration, % motile, morphology  Sperm o Dna is packed into the head  Pituitary gland produces LH and FSH (sertoli cells)- need this and testosterone for spermatogenesis ANSC 1011 Kristy Trahan Genetics  Genetics sets the production limits of a trait while the environment allows expression of the genetic makeup: Nature vs. Nurture o Genes and then the environment (environment is very important)  Why animal breeding and genetics are important o It decides which individuals become parents  Choose most favorable individuals to become parents (economically important traits)  Four Major Branches of Genetics o Molecular o Transmission o Population o Quantitative  Molecular Genetics o Individual DNA makeup; codes for physical traits o Current branch of active research in animal science  Mapping  Gene Function  Marker Development- can do selection based on the different markers on chromosomes  Selection  Transmission Genetics o How traits are inherited o Passed to offspring o Manipulation in order to achieve increase in performance o GMO’s- genetic modified organisms  Population Genetics o Distribution and behavior of genes in various populations  Biological Diversity- the more genetic variation the better chances of survival  Past and present  Quantitative Genetics o Statistical predictions of how all three of the previous branched can be manipulated, and the possible outcomes  Animal breeding- has become more advanced than just animal breeding  Mating decisions through arithmetic to make genetic improvement  Quantitative trait  Anything that can be measured (height weight, etc.)  Animal Breeding: application of all technologies and disciplines of genetics to improve the selection of livestock for increased production  Structure and Function of Genes o DNA is held together by Hydrogen bonds in a double helix structure  Watson and Crick, 1953 o Complementary base pairs: G-C, A-T o DNA  Deoxyribonucleic acid ANSC 1011 Kristy Trahan  The molecule that forms the genetic code o DNA nitrogenous bases  Adenine (A) and Guanine (G)  Purines  Cytosine (C) and Thymine (T)  Pyrimidines o Simple Mendelian Inheritance  Only single pair of genes  Either expressed or not-dominant or recessive  Single strand of DNA, called a chromosome; smaller function unit called a gene, CODES FOR PROTEINS  Chromosomes usually occur in pairs- male and female parent o Chromosomes are homologous  Chromosomes will only bind with the same numbered chromosome  6 with 6, 7 with 7  Cattle: 30 pairs, dogs: 39 pairs, horses: 32 pairs o Gene- the basic physical unit of inheritance consisting of DNA sequence at a specific location on a chromosome o Allele- an even more basic unit of heredity  Two alleles make up a gene (one inherited from the mother and one inherited from the father for most animals) o Exon- a segment of the gene that contains the “code” for the protein that should be produced o Intron- large non-coding region of the gene  Possibly for protection of coding region during replication  Way larger area for more advanced animals o If you cross Angus (black, BB) X Hereford (red, bb), offspring would all be black, Bb; since black coat color is dominant (can also use a punnett square) o Genes of BB, bb are called homozygote or pairing of like genes (homo- same) o Genotype of Bb is called heterozygote or unlike genes (hetero- not same)  Principles of Heredity o Dominance- the interaction of alleles at a single locus, where heterozygotes exhibit a phenotype more like the dominant homozygote genotype  Parents have genotypes of BB X bb for all offspring to have a black coat color o Recessive Trait- when a phenotype can only be observed when an individual inherits a recessive homozygous genotype (bb)  Parents have genotypes of Br X bb to get an offspring with red coat color o Punnett Square  All dominant offspring since they all have a B in their genotype B B B BB BB b Bb Bb ANSC 1011 Kristy Trahan  Some recessive (red coat colored) offspring B b b Bb bb b Bb bb  Exception:  No-dominance- neither allele masks the other and both are expressed o Example: roan color in shorthorns (red and white) o RR- red, RW- roan, WW- white (none of these are dominant)  Quantitative Inheritance o Complex inheritance- many genes influence the economic traits, maybe 10-100  Traits such as growth rate and feed efficiency; polygenes o Genotype: listing of all the specific genes o Phenotype: physical expression of the genetic makeup  Genotype o How determined? (this is where the arithmetic is in genetics)  Measure the phenotype under standard conditions  Phenotype= Genotype (g) + Environment (E)  Phenotype o A good measure of genetics but is not precise  May have a black coat color (dominant) but may have either a BB or Bb genotype, which you can’t tell what the animal carries just by looking at it o Highly heritable traits- genotype and phenotype are very similar  Genetics are the main deciding factor o Lowly heritable traits- genotype and phenotype could be very different  Environment is the main deciding factor  Definitions of Traits o Quantitative Trait- any trait that can be measured on a numerical scale (height, weight, age, size, degree of infection, etc.)  Performance testing in animal production measures quantitative traits o Linkage- markers for a single trait or markers for multiple traits are inherited together because of their proximity to one another on a single loci of a chromosome  a gene for milk production is also linked to fertility in dairy cattle, which is why they have excellent milk production, but have fertility issues o Pleiotropy- the phenomenon where a single gene is influencing multiple traits  one gene can affect the traits of growth, milk production, and meat o Epistasis- when the effect of multiple genes is observed to affect the phenotype of a single trait  Ultimately makes things more complicated  Multiple genes may contribute or affect the growth trait ANSC 1011 Kristy Trahan Animal Breeding  Selection of breeding stock through selection for the next generation using genetic principles- sets the limit of production  Animal breeding- application of all technologies and disciplines of genetics to improve the selection of livestock for increased production  Tools to make genetic improvements o Marker Assisted Selection (MAS) or Genomic Estimated Breeding Value (GEBV)- genetics and statistics combined o Transgenic animals- GMO’s  Only been one animal that has been genetically modified and approved for human consumption (salmon) o Genomics- the whole genome selection (WGS)  Study all the genes and try to figure out what they do o Quantitative (statistics)- widely used today  Using arithmetic o Important concepts-  Pleiotropy- single gene influences multiple traits  Epistasis- multiple genes influence single trait  Heritability o A measure of the amount of phenotypic variation that is due to additive gene effects; the proportion of differences between individuals that is genetic  Two factors: genetics and the environment o Three classes of heritability  Low 0-15% (< .20)- reproductive traits  Fertility, litter size, twinning, age at puberty  The most important because WE SELL THE OFFSPRING  Lowly heritable, so the environment makes a huge difference  Moderate 20-40% (0.20-0.40)- growth traits  Milk yield, feed efficiency, birth weight, weaning weight  Single trait selection can make a lot more improvement more quickly (dairy cattle)- this hindered fertility abilities  High 45-60% (>0.40)- carcass traits  Muscle mass, fatness, mature size, cutability  Highly heritable, so the genes are the largest deciding factor  Selection Tools o EPD’s (Expected Progeny Difference)- used for beef cattle and pigs o PTA’s (Predicted Transmitting Ability)- used for dairy cattle o GEBV’s (Genetic Expected Breeding Value)- combination of single nucleotide polymorphism (SNP) and phenotype/genotype of selected traits (EPD’s), used for dairy cattle, few beef breeds (can DOUBLE genetic progress)  EPD’s- selecting for the offspring!! o Expected Progeny Difference (statistical prediction) o Based upon all records on an animal and all relatives including offspring  Works well for pigs because they have so many offspring o Performance Information- records obtained for economic traits on traits that can be measured ANSC 1011 Kristy Trahan  any data that’s related to economics o EPD= a prediction of the progeny’s performance for economic traits o Contemporary Group= similar animals in a group with similar treatment and equal opportunity to perform  Just like the classroom group o Accuracy of EPD= measure of the reliability of the EPD  Not very accurate if you only keep track of one trait passed onto offspring for one bull o EPD’s are reported in Sire Summaries and can be combined with marker assisted selection (MAS and called GEBV’s)  The bull is half the herd o Can have a pedigree EPD, however these are low in accuracy  Cattle EPD’s (keep getting more complicated) o Growth traits- weaning weight (different for dairy and beef cattle), yearling weight, ADG (average daily gain) o Maternal traits- milk EPD, birth weight  Birth weight is the only trait you don’t want a positive EPD for  The bigger the baby, the more birthing problems that could happen  Birth weight, weaning weight, and yearling weight are all directly connected, so if you choose for one, you choose for all o Reproductive Fertility- scrotal circumference (34 cm, yearling)  The bigger the more sperm that can be produced o Carcass traits- carcass weight, marbling, rib eye area  Marbling- intramuscular fat  The rib eye is related to the overall muscling of the animal  Angus- the prominent breed for beef like the Holstein is the leader of milk production o Origin is Scotland (British breed) o Color- black or red, black is dominant o Most prominent beef cattle breed in U.S. o Popular for carcass traits and maternal traits  Dollar Values o $ values are complex, selection tools o These indexes consider both input and output costs plus EPD’s and accuracy on traits to determine the index o Example: weaned calf value uses birth weight, weaning weight, milk, mature cow and yearling weight, and height EPD’s and costs for this index  Swine EPD’s o STAGES- swine testing and genetic evaluation system o # born alive, 21 day weight (weaning) o Days to 250, back-fat thickness, lb lean o Indexes: SPI, MLI, and TSI  Swine Indexes o SPI- sow productive index  Measure of how productivity based upon number born alive and 21 day weight o MLI- maternal line index ANSC 1011 Kristy Trahan  Used to select replacement females based upon reproductive and post weaning traits o TSI- terminal sire index  Used to select sires whose offspring will all go to market  Days to 250, back-fat, and lb lean  MONEY o Boars and rams: $500-10,000 or more, up to $500,000 o Yearling bull: $2,500-7,000 o Two-year-old bull: $3,500-10,000  Rule of thumb- commercial bull equals to 3 or 5 steers ($2,000 per steer) o Cattle semen- frozen called straws ($20-100) o Pig semen- mainly sold fresh, next day air delivery ($25-500 per dose, requires 2 doses)  So expensive because pig semen doesn’t do well frozen and goes bad quicker than cattle semen, which can withstand being frozen ANSC 1011 Kristy Trahan Genetic Modification in Animals  “Traditional Transgenics”- insertion of recombinant DNA (a transgene) into the genome of an animal o Germ line transmission o Random Insertion o Nuclear Injection (early stage embryos) o Nuclear Transfer (cloning)- method of choice for larger/ domesticated animals  Genomic Editing- molecular tools to make small changes “editing” in the genome at precise locations  Transgenics is adding a transgene; editing is just making a small change in the genome  The Transgene o From a different source (different organism)- it is a gene  DNA sequence that codes for a specific product- a protein  Protein effects desired trait  Regulator sequence- controls expression when and where  Promoter and/or enhancers  Expression in many tissues o Can mix and match the coding and promoters to get a desired result  Tissue specific expression  Put together as a transgene construct- recombinant DNA  Production of DNA o Transgene inserted into plasmid (genetic component of bacteria)  Vector to insert DNA into bacteria o Grown in bacteria o Plasmid DNA isolated o Purified for injection/transfection  Characteristics of Transgenic Animals o Low percentage of animals born are transgenic o Not all express transgene  Random position effects o Select founder animal(s)  In most cases is a single animal used to take transgenes from ANSC 1011 Kristy Trahan o Establish line usually from one animal  Breeding, embryo transfer, cloning? o Transgenics in animals has taken longer because its more expensive than it was for crops and plants  Transgenics by Cloning (Dolly the sheep in 1996) o Transfection of a transgene by electroporation  Millions of cells, cultured cells o Rare events selected for in culture o Cloning captures altered genotype of cells as an animal with germ line transmission of the transgene o Allows precise changes- gene targeting  Disrupt gene function, gene knockout (reduction/elimination of function of a specific gene)  Everything before this was just adding on to the genome and such  Commercialization of Transgenic Animals o One transgenic animal approved for production and sale as food  Transgenic salmon o Transgenic animals for biomedical use  Most immediate application  Pharmaceutical product (anti-coagulating protein, anti-thrombin) from milk of a transgenic goat approved in Europe and US  Numerous models of human disease- laboratory and domestic animals  Test drugs and procedures on transgenic animals  Transgenic Animals in Agriculture (SALMON) o Enhanced production  Overexpression of growth hormone as a transgene o Transgenic salmon produces GH all year from its own GH gene when the water is warm (salmon live in cold water for the most part and is why they grow so slowly)  Transgene: codes for salmon GH  Controlled by promoter from antifreeze protein gene of the artic pout (eel-like fish); expressed when the water is cold  After years of review and endless controversy, the Food and Drug Administration approved the nation's first genetically altered animal -- a salmon engineered to grow twice as fast as its natural counterpart  AquAdvantage, produced by Massachusetts-based AquaBounty, is an Atlantic salmon that contains a growth hormone from a Chinook salmon and has been given a gene from the ocean pout, an eel-like fish. The result is a fish that is large enough for consumption in about a year and a half, rather than the typical three years.  The transgenic salmon grow twice as fast o New “improved” products  Can alter fat content and type- omega 3 fats  Anti-bacterial proteins in milk- can change so these proteins that aren’t usually expressed to be expressed by adding an ezyme  Increased shelf life ANSC 1011 Kristy Trahan  Increased resistance to disease in children resulting from contaminated water o Moving these animals to south America to help out there  Environmental friendly animals  Phytase Pig- reduced phosphorus excretion  Transgenic Animals in Medicine o Production of drugs- cattle, goats, chickens  Unmet need for drug production  Blood clotting factors, human serum albumin  Human antibodies o Transplantation of tissue into humans  Transgenic pigs- organs and tissues for transplantation o Disease models  Laboratory animals  Domestic animals  Molecular Genome Editing o Inducing precise changes in the genome such as deletions or exchanging sequences without introducing a transgene o Three Different Tools to do molecular genome editing  Zinc Finger Nucleases (ZFN)  Transcription Activator-like Effector Nucleases (TALENS)  Clustered Regularly Interspaced Short Palindromic Repeats (CRISPR)  CRISPR- associated endonuclease cas9  The nucleus is directed very specifically to a point in the genome  Can result in insertion/deletion, which causes gene knockout  Another result would be changing an amino acid, which could potentially bring several consequences ANSC 1011 Kristy Trahan  Genomic Editing o Introduction into pronuclear embryos o Site directed editing  Deletions, gene disruption, knockout  Sequence replacement, induce mutation, exchange alleles o Potential in animal breeding  Alternative to marker selection and breeding  Two examples o Horns in reproductive cattle breeds cause many problems and take a lot of time and money to get rid of them  Their genes haven’t been selected for no horns- have been selected more for milk production and such  What they have done is gone into gene editing technology to insert a gene for hornless cattle without losing all the previous gene advancements for milk and reproduction  Beef cattle took a very long time to get to where they are (hornless)  African Swine Fever Virus Tolerance in Pigs o Roslin Institute, University of Edinburgh o Polymorphic variation in RELA gene (immune related gene) between pig species o Warthog RELA and domestic pig RELA differ by 3 amino acids  Bring in those 3 amino acids and get a dramatic impact o Genomic editing of domestic pig RELA gene to resemble warthog RELA o Resistance to African Swine Fever Virus?  Transgenic animals o Large potential  Improved agricultural production  New life-saving drugs o Impact to agriculture yet to be determined o Will genome editing transform the technology?  Already has to some extent  Biomedical applications  Trait altering rather than trait selection  Regulatory status? Not a transgene  In the plant field, genetically modified plants are regulated differently than genetically modified animals  Edited a gene in mushrooms to stop them from turning brown on the shelf- no transgene so the FDA didn’t regulate it o So subtle/small, unlike in animals, where changes are very drastic


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