Transcript Animal Reproduction and Genetics

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
• Colustrum
– First milk
• Gestation
– Time an animal is pregnant
Terminology
• Estrus
– When a female is receptive to be
bred
• Lactation
– Period of time that milk is secreted
by the mammary glands
• Parturition
– The act of giving birth
Breeding Systems
• Objective
– Discuss crossbreeding, grading-up,
inbreeding, linebreeding, and
purebreeding
Breeding Systems
• Pure Breeding
– Registered male and female animals
– Angus X Angus
Breeding Systems
• Cross Breeding
– Mating a male and female of
different breeds
– Angus X Charolais = Crossbreed
Breeding Systems
• Inbreeding
– Mating closely related animals
– Brother X Sister
– Son X Mother
– Father X Daughter
Breeding Systems
• Linebreeding
– Breeding more distant relatives than
inbreeding
– Cousin X Cousin
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
The Female Reproductive
System
Objective: Identify the parts
of the female reproductive
system of livestock
Female Tract
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.
Female Reproductive System
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
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.
Female Reproductive System
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.
Female Reproductive System
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
Female Reproductive System
• Cervix
– Area between
the uterus and
vagina
– Normally closed
– Opens at estrus
and parturition
– (2 -3 inches)
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
Female Reproductive System
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
Reproductive Functions (Female)
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
Reproductive Functions (Female)
3. Gestation
— Fertilization to parturition
— Develop embryo in uterus
4. Parturition
— Expel fully developed young at birth
5. Lactation
— Milk production
Reproductive Functions (Female)
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
Reproductive Terminology
Species
Cows
Ewes
Sows
Hens
Mares
Goats
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
283 - 285 days
Ewe
Sow
Mare
Woman
115
112
330
270
- 142 days
- 115 days
- 345 days
days
Lactation(Milking)
beef 180 - 270 days
dairy 305 - 365 days
60 - 90 - 120 days
21 - 42 days
90 - 150 days
? years
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
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
• BREAK
The Male
Reproductive Tract
Objective: Identify
the parts of the male
reproductive system
of livestock and
poultry
Male Reproductive Tract
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
Male Reproductive Tract
•
Epididymis - Long coiled tube that is
a path for sperm
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–
–
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Provide passageway for sperm out of the
seminiferous tubules
Storage for sperm
Fluid secretion to nourish sperm
Place for sperm maturation
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
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
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
Male Reproductive Tract
• Cowper’s gland
• Also called the Bulbourethral gland
• Paired organs
• cleans the urethra prior to semen
passage
Male Reproductive Tract
Reproduction in
Poultry
Objective: Specify how the
reproductive system for
poultry functions
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
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
Poultry Reproduction
In your notes, define the following
poultry reproductive terms and tell
how they differ from livestock we have
studied so far:
Follow the
Lecture
•Papilla
•Testicles
•Cloaca
•Vent
•Ovary
•Magnum
•Isthmus
•Uterus
•Vagina
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.
Animal Reproduction and
Genetics
Objective: Describe the cell and
process involved in cell division
including how genes affect the
transmission of characteristics
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
Animal Cell
Nucleus
Cytoplasm
Cell
Membrane
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
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
Fertilization
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
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–
–
–
–
Cattle 30
Swine 19
Horses 33
Chickens 6
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
Assignment
1. Read pages 186
• Livestock and Poultry Production
textbook
2. Complete problems 1-9
3. Write the question and provide a
short answer in complete
sentences.
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
Genes
Example:
The dominant gene is written- P
The recessive gene is written-p
P= Polled
p= horned
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
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
Punnett Square
P= Polled
p= horned
Example:
• Two polled cattle
that are
homozygous for
the polled trait
Polled Dam
P
P
P
PP
PP
P
PP
PP
Punnett Square
N= Normal size
n= Dwarfism
Example:
• Normal size in
cattle is dominant
to dwarfism
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?
Normal Dam
N
n
N
NN
Nn
n
Nn
nn
Result: one out of every four births
could result in a dwarf animal (1:2:1)
Assignment
(Alternatives are horned
and red)
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)
9:3:3:1
Heritability
• Objective:
– Discuss hertability estimates for beef
and swine
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
Heritability
• Swine rates are usually lower than
cattle
• Heritiability for carcass traits are
higher than reproductive traits
• Estimates vary from 0 to 70%
Birth weight
40%
Weaning Weight
25-30%
Yearling Weight
60%
Fertility
10%
Tenderness
60%
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