Animal Reproduction and Genetics

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Animal Reproduction and Genetics
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Terminology

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

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Terminology

• Castration
• Removing the testicles of the male to prevent
  breeding
• Colustrum
• First milk
• Gestation
• Time an animal is pregnant

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Terminology

• 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

X
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Breeding Systems

• Cross Breeding
• Mating a male and female of different breeds
• Angus X Charolais Crossbreed

X
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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
Species Act Offspring Cows calving calf Ewes
lambing lamb Sows farrowing pig Hens hatchin
g chick Mares foaling foal Goats kidding kid
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Reproductive Functions (Female)

• Gestation and Lactation Periods
• Species Gestation Period Lactation(Milking)
• Cow 275 - 285 days beef 180 - 270
  days dairy 305 - 365 days
• Ewe 115 - 142 days 60 - 90 - 120 days
• Sow 112 - 115 days 21 - 42 days
• Mare 330 - 345 days 90 - 150 days
• Woman 270 days ? years

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Reproductive Functions (Female)

• Estrous period length by species
• Cow 12 - 18 hours
• Ewe 24 - 36 hours
• Sow 48 - 72 hours
• Mare 90 - 170 hours
• Hens Women none

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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
• Ewe 16 - 17 days
• Sow 19 - 21 days
• Mare 21 - 24 days
• Woman 28 days
• Hen none

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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

• Cowpers 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 females
  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

Use page 190 in your textbook
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Assignment

• 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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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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Fertilization

• 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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Fertilization
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Chromosomes

• 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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Genes

• 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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Assignment

• 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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Genes

• 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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Genes

• Example
• 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
• Example
• 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
• Example
• Normal size in cattle is dominant to dwarfism

Normal Dam
Sire Carrier
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Punnett Square

• N Normal size
• n Dwarfism
• Example
• 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 (121)
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Assignment

• Complete a Punnett Square for two animals that
  are heterozygous for two traits
• PolledP
• Black B
• (Alternatives are horned and red)

Dam
Sire
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Answer

• A Punnett Square for two animals that are
  heterozygous for two traits
• PolledP
• Black B
• (Alternatives are horned and red)

Dam
Sire
9331
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Heritability

• Objective
• Discuss hertability estimates for beef and swine

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Heritability

• 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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Heritability

• 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 weight 40 Weaning Weight 25-30 Yearling
Weight 60 Fertility 10 Tenderness 60
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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