Transcript Animal Reproduction and Genetics

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 produced after a mammal gives
birth that contains antibodies needed for
immunity.
• Gestation
– Time an animal is pregnant
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Terminology
• Estrus
– When a female is receptive to be bred (also
called ‘in heat’)
• Lactation
– Period of time that milk is secreted by the
mammary glands
• Parturition
– The 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 crossbred females (dams)
– Yorkshire boar 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
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.
• 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
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
3. passageway for fetus at parturition
• Vulva - extended genitalia; opening for both urinary and
genital tracts
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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
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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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Ovulation Rates
Ovulation Rates by Species
Cow1 egg per estrus
Ewe1 to 3 eggs per estrus
Sow10 to 20 eggs per estrus
Mare1 egg per estrus
HenApprox. 28 eggs per month
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Reproductive Terminology
Species
Cows
Ewes
Sows
Hens
Mares
Goats
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Act
Offspring
hatching
chick
Species
Cows
Ewes
Sows
Hens
Mares
Goats
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Act
calving
lambing
farrowing
hatching
foaling
kidding
Offspring
calf
lamb
pig
chick
foal
kid
Reproductive Functions (Female)
Gestation and Lactation Periods:
Species
Cow
Gestation Period
275 - 285 days
Lactation(Milking)
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
How to AI a Cow
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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 (connected to each testicle)
–
–
–
Provide passageway for sperm out of the seminiferous
tubules
Storage for 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
• 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, covered by a sheath
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Male Reproductive Tract
Accessory Glands:
– Seminal Vesicles
• Function: Produce a fluid that protects and
transports sperm.
• Description: A gland that opens into urethra.
– Prostate Gland
• Function: Produces a fluid that is mixed with the
seminal fluid.
• Description: Gland near the urethra and bladder.
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Male Reproductive Tract
• Cowper’s Gland
– Function: Produces a fluid that moves
down the urethra ahead of the seminal
fluid. It cleans and neutralizes the
urethra to protect the sperm.
– Description: A gland near the urethra.
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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
• Ovary- poultry only have one functioning ovary as
compared to livestock animals.
– Function: Produces ova and hormones. The yolk of
an egg is the ovum.
– Description: An attached cluster of yellow, round egg
yolks.
• Infundibulum
– Function: The place where fertilization takes place.
– Description: Funnel shaped structure located just
below the ovary. It is the start of the oviducts.
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Reproduction in Poultry
• Oviduct- tube like structure that consists of five
parts:
– Magnum- secretes the thick egg white or
albumen.
– Isthmus- adds the two shell membranes.
– Uterus- secretes the thin white, the shell and
the shell pigment.
– Vagina- holds the egg until it is laid.
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Reproduction in Poultry
• Cloaca
– Function: Location where the papilla of the male bird
deposits semen. Egg also passes through this part.
– Description: Located between vent and base of
oviduct.
• Vent
– Function: Expel egg, liquid and solid waste.
– Description: Outside opening to the poultry
reproductive tract.
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Reproduction in Poultry
• The major difference between mammals and poultry
reproductive systems is that the embryo of livestock
develops inside the female’s body and the poultry
embryo develops outside the body. Papilla is the organ
in male poultry’s cloaca wall that puts the sperm in the
hen’s reproductive tract
• Chickens (domestic birds) have only the left ovary and
oviduct functional at maturity (produce eggs). The right
ovary and oviduct do not function.
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Reproduction in Poultry
• Egg- function is reproduction, but is eaten as food by
humans and wild animals.
• Domestic chickens lay an egg every 24-28 hours
regardless even if sperm are not present. Commercially
sold eggs are not fertilized.
• Incubation time for chicken eggs is 21 days.
• Turkeys and ducks eggs incubation is 28 days.
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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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Parts of a cell
• Protoplasm- the
material or
contents inside of
a cell.
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Parts of a cell
• Cell Membrane- a
thin layer of protein
and fat that
surrounds the cell.
Some substances
can pass into the
cell and the
membrane blocks
others materials
from entering.
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Cell Membrane
Parts of a cell
• Centrosome- small
body where the
microtubules are
made. The
centrosome
divides during
mitosis.
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Centrosome
Parts of a cell
• Nucleus- gives cell
ability to grow,
digest food and
divide. Contains
chromosomes and
DNA.
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Nucleus
Parts of a cell
• Cytoplasm- a
jellylike substance
that gives the cell
shape and
contains
components
necessary for cell
functions.
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Cytoplasm
Parts of a cell
• Golgi bodylocated near the
nucleus and
produces the
membrane that
surrounds the
lyosomes.
Golgi body
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Parts of a cell
• Lyosome- round
shaped organelles
that contain
digestive enzymes
that allow for
digestion of cell
nutrients.
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Lysosome
Parts of a cell
• Mitochondrionrod-shaped
organelles that
convert the energy
stored in glucose
into ATP
(adenosine
triphosphate).
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Mitochondrion
Parts of a cell
• Nuclear
membrane- the
membrane that
surround the
nucleus.
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Nuclear
membrane
Parts of a cell
• Nucleolusorganelle found
inside the nucleus.
Produces
ribosomal RNA.
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Nucleolus
Parts of a cell
• Endoplasmic
Reticulumtransports
materials through
the cell.
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Rough ER
Smooth ER
Parts of a cell
• Vacuole- fluid filled
membrane that fills
with food and
waste products
inside the cell.
Vacuole
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Parts of a cell
• Ribosome- site of
protein synthesis.
Ribosome
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Cell Division
• Two types of cell division that we must know:
– Mitosis
– Meiosis
Videos:
http://www.youtube.com/watch?v=C6hn3sA0ip0
http://www.youtube.com/watch?v=-DLGfd-Wpr4
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Mitosis – what is it?
• Mitosis is a type of cell division that increases
the total number of cells and results in animal
growth with the chromosome pairs being
duplicated in each new cell.
– Results in animal growth.
– Animals begin as a single cell.
– Chromosomes are duplicated in each new cell
as division occurs.
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Mitosis
There are four typical stages in mitosis cell
division:
1.Prophase
2.Metaphase
3.Anaphase
4.Telophase
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Mitosis – Stage 1
• Prophase- the nucleolus
disappears and centrioles
move to opposite ends of the
cell. Fibers begin to form and
extend from the centromeres.
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Mitosis – Stage 2
• Metaphase- spindle
fibers align the
chromosomes along the
middle of the cell
nucleus.
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Mitosis – Stage 3
• Anaphase- the paired
chromosomes separate and
move to opposite sides of
the cell.
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Mitosis – Stage 4
• Telophase- nuclear
membrane forms around
the newly divided
chromosomes and cell
membrane begins to
contract.
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Now to meiosis…..
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Cell Division
• Two types of cell division that we must know:
– Mitosis
– Meiosis
Videos:
http://www.youtube.com/watch?v=C6hn3sA0ip0
http://www.youtube.com/watch?v=-DLGfd-Wpr4
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Meiosis
• Meiosis is a type of cell division that produces
the sex cells or gametes that have ½ the number
of chromosomes that body cells have.
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Meiosis
• Gamete Formation
– One set of chromosomes come from the
sperm and one from the ovum.
– The zygote that is created during fertilization
has chromosomes from each parent.
Chromosomes match up with one another
based on the genetic information they carry.
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Meiosis
• Sex cell formation of the sperm and ova are also
produced through meiosis:
– Production of sperm is called
spermatogenesis.
• Male animals begin producing sperm at sexual
maturity.
• Spermatocytes divide into spermatids through
meiosis.
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Meiosis
• Sex cell formation of the sperm and ova are also
produced through meiosis:
– Production of an ovum is called oogenesis.
• Females also begin releasing ova at sexual
maturity.
• The oocytes divide and form an ovum. The ovum
contains cytoplasm and stored food. It provides
nourishment for the zygote and embryo.
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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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Meiosis – putting it all back
together…
https://highered.mcgrawhill.com/sites/0072495855/student_view0/chapt
er28/animation__how_meiosis_works.html
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Chromosomes
• Rod shaped bodies
• Made of protein
• Found in the cell
nucleus
• Exist in pairs except
for gamete cells
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• The number of
chromosome pairs
differ for various
animals
–
–
–
–
–
Cattle 30
Swine 19
Horses 32
Chickens 39
Humans 23
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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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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Genotypes
• Three class genotypes
Homozygous Dominant = PP
Homozygous Recessive = pp
Heterozygous = Pp
• P = Polled & p = horned
• Six possible crosses:
PP x PP, PP x Pp, PP x pp, Pp x Pp, Pp x pp,
pp x pp
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Punnett Square
Polled Dam
P= Polled
p= horned
Example:
• Two polled cattle that are
homozygous for the polled trait
Genotypic Ratio: 4PP : 0
Phenotypic Ratio:4 polled animals
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Polled Dam
P
P
P
PP
PP
P
PP
PP
Punnett Square
Normal Dam
N= Normal size
n= Dwarfism
Example:
• Normal size in cattle is
dominant to dwarfism
Genotypic Ratio:
Phenotypic Ratio:
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Normal Dam
N
N
N
NN
NN
n
Nn
Nn
Punnett Square
N= Normal size
n= Dwarfism
Example:
• What if both parents are
carriers for a trait or
disorder?
Genotype:
Phenotype:
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Normal Dam
Normal Dam
N
n
N
NN
Nn
n
Nn
nn
Assignment
(Alternatives are horned and
red)
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Dam
Sire
Complete a Punnett
Square for two
animals that are
heterozygous for
two traits:
• Polled=P
• Black= B
Answer
Sire
A Punnett Square
Dam
for two animals
PB
Pb
pB
pb
that are
heterozygous for PB PPBB PPBb PpBB PpBb
two traits:
Pb PPBb PPbb PpBb Ppbb
• Polled=P
pB PpBB PpBb ppBB ppBb
• Black= B
pb PpBb Ppbb ppBb ppbb
(Alternatives are horned
and red)
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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%
• Traits with low heritability estimates are
improved most through environment, and those
traits with high heritability estimates are
improved most by selective breeding and
environmental improvements.
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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
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