Transcript Animal Reproduction and Genetics

Animal Reproduction and
Genetics
Estrus Cycle
Time during which the female will
accept the male for breeding
Length of estrus cycle in both
cattle and swine is about 21 days
The actual time a cow is in heat is
about 16-18 hours, sow about 2
days
Estrus Cycle
http://ww
w.hyperi
onfarm.c
om/Estro
us.htm
Estrus Cycle
There are several signs of heat
including swelling of the vulva,
frequent urination, nervousness or
restlessness, mounting other
animals and letting other animals
mount.
Estrus Cycle
Best indication that a cow is ready
to breed is when she stands when
mounted by another cow
Ovulation
Number of young that animals
gives birth to at one time is
indication of number of eggs
released or ovulated
Sows: 1-15
Cows generally 1
Ovulation-Fertilization
http://www.visembryo.co
m/baby/stage1.html
Ovulation
At ovulation, fertilization will take
place and the animal will become
pregnant if the animal is bred so
that the egg cell and live sperm are
present at the same time
Fertilization
http://www.visembryo.com/baby/stage2.html
Artificial Insemination
Placing sperm in the female
reproductive tract using other than
natural processes
Artificial Insemination
Cow: person’s hand is inserted into
the cow’s rectum to grasp the
cervix, and then then inseminating
tube or rod is used to deposit the
bull semen from the middle of the
cervix to just into the body of the
uterus when the cow is in heat
AI- transfer gun
http://www.agtechinc.com/store/products.cfm
?action=showThumb&start=1&DeptCode=38
Artificial Insemination
Advantages
Wider variety of superior bulls
Increases number of cows bred to
superior bulls
Reduces the spread of diseases
Don’t have to keep bulls on the
farm
Artificial Insemination
Disadvantages:
Requires a trained inseminator
Requires more time and herd
supervision
Embryo Transfer
Superovulation of donor with
hormones
Artificial insemination
Flush embryos and remove with
catheter
Isolate and classify embryos
Embryo Transfer
Store embryos in liquid nitrogen
Transfer embryos to recipient cows
Diagnose pregnancy 1 to 3 months
later
Birth 9 months after transfer of
embryos
Embryo Transfer
Advantage:
Genes of the female (dam) can be
passed to more offspring faster
than natural breeding
Embryo Transfer
http://www.agtechinc.com/overview/
Cloning Cattle Using
Nuclear Transfer
Process:
Flush and remove embryos with
catheter same as regular ET
Filter the flushed liquid to remove
embryos
Remove genetic material from
recipient oocytes
Cloning Cattle Using
Nuclear Transfer
The nuclei are removed through
microsurgery
The nuclei are separated and each
one is transferred to an unfertilized
egg cell that has had its nucleus
removed (thus the term nuclear
transfer)
Nuclear transfer
http://www.roslin.ac.uk/library/
Cloning Cattle Using
Nuclear Transfer
 Plugs with 3 or 4 embryos are placed
in oviducts for 5 to 6 days to develop
to the 32 to 64 cell stage
 Embryos are removed and placed into
surrogate mothers, frozen for long term
storage or used to produce another
generation of cloned embryos
Stages of Nuclear transfer
http://www.roslin.
ac.uk/library/
Cloning Cattle Using
Nuclear Transfer
Advantages:
Increased herd uniformity
Increase herd quality
Produce genetically identical
animals
Parturition Process
Begins when increased estrogen
causes the uterus muscles to
contract
First water bag appears, enlarges
and breaks open
Parturition Processwater bag breaking
http://www.lapc.cc.ca.us/usr/shapirls/Parturition_in_the_horse.htm
Parturition Process
Soon afterwards, the second water
bag containing the fetus breaks
open and the presentation of the
animal begins
Parturition process- amnion sac
http://www.lapc.cc.ca.us/usr/shapirls/Parturition_in_the_horse.htm
Parturition Process
Normal position of the fetus at
birth is front feet first, followed by
the nose, then the head, shoulders,
middle, hips, rear legs, and feet
Parturition process- foaling
http://www.lapc.cc.ca.us/usr/shapirls/Parturition_in_the_horse.htm
Parturition Process
Several hours later, the placenta
and other membranes (afterbirth)
are expelled.
Afterbirth must be expelled or the
animal will become sick
Parturition process- placenta
http://www.lapc.cc.ca.us/usr/shapirls/Parturition_in_the_horse.htm
Parturition Process
Any presentation that does not
have the order as previously stated
is abnormal and could cause
problems such as death of the
young or the mother
Body Conditioning
Important because it affects
conception in cows, and the goal is
to have each cow give birth and
wean a calf every year
Underconditioned or thin cows are
the major cause of all reproductive
problems
Timing
Size is the most important
consideration when breeding
heifers that are sexually mature
(550-750 pounds)
Age is second (2 years calve)
Calving in the herd should occur
during a 40 to 60 day period
Synchronization of Estrus
Use of hormones to cause all the
female sin a herd to come into heat
in a short period of time
Shorter breeding and calving
seasons are advantages
Multiple farrowing
Arranging the breeding program so
that groups of sows farrow at
regular intervals throughout the
year
The number in the group should
match facilities
Advantages
Higher average prices for hogs sold
because sales are spread
throughout the year
Spreading income throughout the
year
More efficient use of facilities
Disadvantages
Requires better management
Requires a year-round labor supply
Other considerations
Because the producer needs to
make maximum use of farrowing
facility capacity, it is very
important that conception rates and
litter sizes be the best possible
Other considerations
Disease prevention and control,
proper boar to sow ratio and
breeding each sow at least twice
during each heat period (multiple
breeding) increase conception rates
Reproduction Practices in Poultry
AI is used for large, heavy breeds
of turkeys because of low fertility
rates and eh large size of males
(toms) used for natural breeding
Reproduction Practices in Poultry
Since chickens and turkeys come
from fertile eggs, reproduction
efficiency involves the eggs being
fertile, the incubation process and
control of diseases
Reproduction Practices in Poultry
In breeding flocks, eggs are
gathered several times each day
and packed with the large end up to
protect the air cell
Hatching eggs are fumigated with
chemicals to help prevent the
spread of egg-borne diseases
Palpation
 The process of diagnosing pregnancy
by feeling the reproductive tract of a
cow
 Experience is necessary for accuracy
because the person doing the diagnosis
compares the feel and size of different
parts of the tract to determine the stage
of pregnancy
Palpation
Good website
http://www.animal.ufl.edu/hansen/pr
otocols/palpation.manual.htm
http://www.breeders.umn.edu
/ansc3023/ai/sld011.htm
Palpation
Must use plastic sleeves and
lubricant to palpate in the rectum
Breeding records are used to
indicate when the cow was bred
and when to check for pregnancy
Genotype
Kinds of gene pairs the animal has
Genes
Dominant: hides or dominates the
effect of the other gene in the pair
and is indicated by upper case
letters
Recessive: is hidden or covered by
the gene in the pair and is indicated
by lower-case letters
Gene pairs
Homozygous carries two genes for
the same trait (uppercase letter or
lowercase letter)
Heterozygous carries two different
genes for the same trait (uppercase
letter and lowercase letter)
Gene pairs
See Gillespie p 180-2
IMS p 8406 p 8834-A, B
Sex determination
After meiosis, one half the sperm
carries an X chromosome and one
half carries a Y
All ova carry an X chromosome
In mammals XX females, XY male
Sex determination in poultry
Males carry ZZ
Females carry ZW
Sex is determined by females
Sex Linked Characteristics
Some traits are carried on X some
on Y
– Those on Y are only transmitted
from fathers to sons
– Certain genes are expressed only in
one sex even if carried on both
chromosomes (lactation, egg laying,
rooster tail feathers, etc.)
Terms
 Sex linked are often recessive and
covered by dominant genes
 Incomplete Dominance: takes place
when one gene does not completely
hide or dominate another gene, mixture
of two genes (example roan: combo of
red/white)
Terms
Linkage: tendency for certain traits
to appear in groups in the offspring
because the genes for those traits
are located near each other on the
chromosome and stay together to
pass traits in groups
Terms
Crossover: when chromosomes
cross over one another and split to
form new chromosomes with
different combinations of genes
Mutation: when a new trait appears
which did NOT exist in the
genetics of either parent
Punnett Square
See Gillespie p 181-4
THE END!!!!!