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Animal Reproduction and Genetics. Terminology. Objective: Define terminology related to reproductive management and breeding systems including castration, colustrum, estrus, gestation, lactation and parturition. . Terminology. Castration Removing the testicles of the male to prevent breeding

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Animal Reproduction and Genetics

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Animal reproduction and genetics l.jpg

Animal Reproduction and Genetics

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  • Objective:

    • Define terminology related to reproductive management and breeding systems including castration, colustrum, estrus, gestation, lactation and parturition.

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  • Castration

    • Removing the testicles of the male to prevent breeding

  • Colustrum

    • First milk

  • Gestation

    • Time an animal is pregnant

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  • Estrus

    • When a female is receptive to be bred

  • Lactation

    • Period of time that milk is secreted by the mammary glands

  • Parturition

    • Than act of giving birth

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Breeding Systems

  • Objective

    • Discuss crossbreeding, grading-up, inbreeding, linebreeding, and purebreeding

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Breeding Systems

  • Pure Breeding

    • Registered male and female animals

    • Angus X Angus


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Breeding Systems

  • Cross Breeding

    • Mating a male and female of different breeds

    • Angus X Charolais = Crossbreed


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Breeding Systems

  • Inbreeding

    • Mating closely related animals

    • Brother X Sister

    • Son X Mother

    • Father X Daughter

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Breeding Systems

  • Linebreeding

    • Breeding more distant relatives than inbreeding

    • Cousin X Cousin

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Breeding Systems

  • Grading-Up

    • Mating purebred male (sires) to unregistered or corssbred females (dams)

    • Yorkshire bore X Yorkshire/Hampshire sow

    • Hybrid Vigor

      • Superior traits from crossbreeding

      • Offspring are better than parents

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The Female Reproductive System

Objective: Identify the parts of the female reproductive system of livestock

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Female Tract

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Female Reproductive System

  • Ovary - the ovary is comparable to the male testicle and is the site of gamete production.

    • A bovine animal has 20,000 potential eggs per ovary, while a human female has 400,000 potential eggs per ovary.

    • Ova are fully developed at puberty and are not continuously produced as in the male.

    • All species contain two functional ovaries except for the hen which has only a left functioning ovary.

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Female Reproductive System

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Female Reproductive System

The ovaries have three major functions:

  • Gamete production

  • Secrete estrogen (hormone)

    • absence of muscle development

    • development of mammary glands

    • development of reproductive systems and external genitalia

    • fat deposition on hips and stomach (source of energy)

    • triggering of heat

  • Form the corpus luteum

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Female Reproductive System

  • Infundibulum - the funnel shaped portion of the fallopian tube near the ovary that catches the ovulated egg.

  • Fallopian Tubes (or Oviducts) - pair of small tubes leading from the ovaries to the horns of the uterus (5 - 6 inches).

    • Fertilization occurs in the oviduct.

    • Egg travels from ovary to uterine horn in 3 - 4 days.

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Female Reproductive System

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Female Reproductive System

  • Uterine Horn - The anterior, divided end of the uterus in the cow, ewe, and mare. Sow has only 2 horns, no body, woman has no horns, only body.

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Female Reproductive System

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Female Reproductive System

Uterus - Muscular sac connecting fallopian tubes and cervix

1. Sustains the sperm and aids in its transport 2. Supports embryo and fetus during gestation

3. Expels fetus at parturition

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Female Reproductive System

  • Cervix

    • Area between the uterus and vagina

    • Normally closed

    • Opens at estrus and parturition

    • (2 -3 inches)

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Female Reproductive System

  • Vagina - the female organ of copulation

    1. admits penis

    2. receives semen (except in sow)

    3. passageway for fetus at parturition

  • Bladder - storage organ for urine

  • Vulva - extended genitalia; opening for both urinary and genital tracts

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    Female Reproductive System

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    Reproductive Functions (Female)

    Steps in the female reproductive process:

    1. Ovulation

    • Produce gamete (ova or ovum)

    • Release of egg(s)

    • Infundibulum pushes the ovum into the fallopian tube

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    Reproductive Functions (Female)

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    Reproductive Functions (Female)

    2. Estrus (heat, estrous period)

    • Period of time when a female will accept a male in copulation

    • The female must stand (standing heat) to be mounted before the reproductive process can begin

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    Reproductive Functions (Female)

    3. Gestation

    • Fertilization to parturition

    • Develop embryo in uterus

      4. Parturition

    • Expel fully developed young at birth

      5. Lactation

    • Milk production

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    Reproductive Functions (Female)

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    Ovulation Rates

    Ovulation Rates by Species

    Cow-1 egg per estrus

    Ewe-1 to 3 eggs per estrus

    Sow-10 to 20 eggs per estrus

    Mare-1 egg per estrus

    Hen-Approx. 28 eggs per month

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    Reproductive Terminology

    • SpeciesAct Offspring

    • Cowscalvingcalf

    • Eweslambinglamb

    • Sowsfarrowingpig

    • Henshatchingchick

    • Maresfoalingfoal

    • Goatskiddingkid

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    Reproductive Functions (Female)

    Gestation and Lactation Periods:

    SpeciesGestation PeriodLactation(Milking)

    Cow275 - 285 daysbeef 180 - 270 daysdairy 305 - 365 days

    Ewe115 - 142 days60 - 90 - 120 days

    Sow112 - 115 days21 - 42 days

    Mare330 - 345 days90 - 150 days

    Woman270 days? years

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    Reproductive Functions (Female)

    Estrous period length by species:

    Cow12 - 18 hours

    Ewe24 - 36 hours

    Sow48 - 72 hours

    Mare90 - 170 hours

    Hens & Womennone

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    Reproductive Functions of the Female

    Estrous cycle - time from one heat period (or menstrual cycle) to the next.

    Length of estrous cycle by species:

    Cow 19 - 21 days

    Ewe16 - 17 days

    Sow19 - 21 days

    Mare21 - 24 days

    Woman28 days


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    The Male Reproductive Tract

    Objective: Identify the parts of the male reproductive system of livestock and poultry

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    Male Reproductive Tract

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    Male Reproductive Tract

    • Scrotum - external sac that holds testicles outside of the body to keep sperm at 4-5oF cooler than the body temperature

    • Testicles - the primary male organs of reproduction

      • to produce sperm

      • to secrete testosterone

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    Male Reproductive Tract

    • Epididymis - Long coiled tube that is a path for sperm

      • Provide passageway for sperm out of the seminiferous tubules

      • Storage for sperm

      • Fluid secretion to nourish sperm

      • Place for sperm maturation

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    Male Reproductive Tract

    • Vas Deferens - slender tube from epididymis to urethra which moves sperm to the urethra at ejaculation

    • Urethra - long tube from bladder to penis; passageway for urine and sperm out of the body

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    Male Reproductive Tract

    • Penis - male organ of copulation which conveys semen and urine out of the body

    • Penis retractor muscle - allows extension and retraction of the penis; sigmoid flexure extends in copulation

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    Male Reproductive Tract

    Accessory Glands:

    • Seminal vesicles- add fructose and citric acid to nourish the sperm

    • Prostate Gland - located at the neck of the bladder

      • cleans the urethra prior to and during ejaculation

      • provides minerals for sperm

      • provides the medium for sperm transport

      • provides the characteristic odor of semen

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    Male Reproductive Tract

    • Cowper’s gland

      • Also called the Bulbourethral gland

      • Paired organs

      • cleans the urethra prior to semen passage

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    Male Reproductive Tract

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    Reproduction in Poultry

    Objective: Specify how the reproductive system for poultry functions

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    Reproduction in Poultry

    The poultry oviduct has five parts:

    1) Vagina

    • Holds the egg until laid

      2) Uterus

    • Secretes the shell

      3) Isthmus

    • Adds the two shell membranes

      4) Magnum

    • Secretes the albumen

      5) Infundibulum

    • Where fertilization takes place

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    Reproduction in Poultry

    • Major difference:

      • Embryo of livestock develop inside the female’s body while the embryo of poultry develops inside the egg.

    • Poultry only have the left ovary and oviduct when mature

    • The yoke is the ovum

    • Chicken Incubation

      • 21 days

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    Poultry Reproduction

    In your notes, define the following poultry reproductive terms and tell how they differ from livestock we have studied so far:

    • Ovary

    • Magnum

    • Isthmus

    • Uterus

    • Vagina

    • Papilla

    • Testicles

    • Cloaca

    • Vent

    Follow the Lecture

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    Build a crossword puzzle containing 12 reproductive terms from your class notes. Have another student complete and sign your crossword puzzle. The assignment as well as your other assignment from the handout is due at the end of class.

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    Animal Reproduction and Genetics

    Objective: Describe the cell and process involved in cell division including how genes affect the transmission of characteristics

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    Animal Cell

    • The body is made up of millions of tiny cells

    • Most of the cell is made up of protoplasm

    • Cell parts:

      • Nucleus

      • Cytoplasm

      • Cell membrane

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    Cell Membrane

    Animal Cell

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    Cell Division

    • Mitosis

      • Increases total number of cells

      • Results in animal growth

      • Chromosomes pairs are duplicated

    • Meiosis

      • Produces gametes

      • Only have one-half the chromosomes of normal cells

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    • When the sperm from a male reaches the egg from a female

    • Two cells join to form a complete cell

    • Pairs of chromosomes are formed again

    • Many different combinations of traits are formed

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    Rod shaped bodies

    Made of protein

    Found in the cell nucleus

    Exist in pairs except for gamete cells

    The number of chromosome pairs differ for various animals

    Cattle 30

    Swine 19

    Horses 33

    Chickens 6

    Humans 23


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    • Located on chromosomes

    • Thousands found in each animal

    • Control inherited characteristics

      • Carcass traits

      • Growth rate

      • Feed efficiency

    • Two types of inherited traits

      • Dominant

      • Recessive

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    • Read pages 186

      • Livestock and Poultry Production textbook

    • Complete problems 1-9

    • Write the question and provide a short answer in complete sentences.

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    • Dominant gene

      • Hides the effect of another gene

      • Polled condition in cattle is dominant

      • The gene is represented by a capital letter

    • Recessive

      • Gene that is hidden by another

      • The gene is represented by a lower case letter

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    The dominant gene is written- P

    The recessive gene is written-p

    P= Polled

    p= horned

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    Homozygous and Heterozygous

    • Homozygous gene pair

      • Carries two genes for a trait

      • Polled cow might carry the gene PP

    • Heterozygous

      • Carries two different genes that affect a trait

      • Polled cows might carry a recessive gene with the dominant Pp

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    Predicting Genotype

    • Genotype-kind of gene pairs possessed

    • Phenotype- the physical appearance of an animal

    • Punnett squares are used to predict genotypes and phenotypes of animals

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    Punnett Square

    P= Polled

    p= horned


    • Two polled cattle that are homozygous for the polled trait

    Polled Dam

    Polled Sire

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    Punnett Square

    N= Normal size

    n= Dwarfism


    • Normal size in cattle is dominant to dwarfism

    Normal Dam

    Sire Carrier

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    Punnett Square

    N= Normal size

    n= Dwarfism


    • What if both parents are carriers for a trait or disorder?

    Normal Dam

    Sire Carrier

    Result: one out of every four births could result in a dwarf animal (1:2:1)

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    Complete a Punnett Square for two animals that are heterozygous for two traits:

    • Polled=P

    • Black= B

      (Alternatives are horned and red)



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    • A Punnett Square for two animals that are heterozygous for two traits:

    • Polled=P

    • Black= B

    • (Alternatives are horned and red)




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    • Objective:

      • Discuss hertability estimates for beef and swine

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    • Estimated the likelihood of a trait being passes on from the parent to the offspring

      • Low heritability

        • slow herd improvement

      • High heritability

        • faster improvement

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    • Swine rates are usually lower than cattle

    • Heritiability for carcass traits are higher than reproductive traits

    • Estimates vary from 0 to 70%

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    Heritability Estimates

    Birth weight40%

    Weaning Weight25-30%

    Yearling Weight60%



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    Heritability Review

    • Herd improvement

      • slow for low heritability

      • faster for high heritability

    • Estimates are higher for:

      • beef compared to swine

      • carcass traits compared to repro

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