Transcript Swine Breeding and Genetics

Swine Breeding, Genetics and
Reproduction
Dr. Randy Harp
The Stress Report
 Meat
quality is the key to what we are
selling
 Packers figure out how to identify poor
quality and where it comes from
 Packers are pushing to get leaner hogs, yet
not with poor quality
 Porcine Stress Syndrome (PSS)
Two types of PSS genes
 Napole
(RN) and Halothane (HAL)
 RN is a dominant allele (RN-) and a
recessive allele (rn+) that is simply
inherited on one locus
 The RN- reduces the ultimate pH of the
muscle that reduces WHC and increases
purge esp. in the ham and loin
PSS cont.
 HAL
- is a mutation on chromosome 6 of
the pig at nucleotide 1843. It increases lean
meat content but enhances PSE and PSS.
 PSS – animal lacks the ability to adapt to
stress
 HAL is inherited also from a single locus
and there are two alleles (N normal and
n mutant)
PSS cont.
 HAL
has three possibilities
 NN normal
 Nn carrier
 nn mutant (stress positive)
 DNA probe now can identify all three
genotypes
 30-50% of carriers will produce inferior
muscle pork quality
Pork Quality
 All
poor pork quality is not due to HAL
only- about 20 % of poor pork quality was
negative for HAL
 Yet, eliminating HAL positive pigs would
drastically help the pork quality issues
PSS- genetic influence
 worst
condition is homozygous recessive
for HAL and RN
 produces carcasses that are watery, chewy
and undesirable
 they reproduce at lower rates and often die
before they get into the breeding herd
 heterozygous- don’t show signs but carry
the potential for stress
PSS
 either
homoz. or heteroz. will cause
problems either in transit or at the packing
plant
 Lauren Christian of Iowa State says to mate
the carrier sows to totally free boars
 if you have any stress genes in the herd,
look at them as though they are strictly
terminal (yet try to stay away from it)
PSS
Nebraska SPF claims that they were the first to
have stress free herds
 American Yorkshire Club first to take a stand
against the stress gene
 any York boar used for AI or natural had to be test
by DNA test and be free in order to be registered
 Duroc & Chester White Associations were second
and third to pass similar rules

Birth Defects
 estimated
one out of one hundred has some
birth defect
 around 150 different known birth defects
 only 13 % are known to be due to genetics
 about 13 % due to environmental effects
 therefore, 75 % unknown
if problems pop up, ask four
questions:
 were
the defective pigs sired by the same
boar
 does the condition trace back to one sire, if
every litter was effected
 are the matings due to abnormal inbreeding
 were the dams afflicted treated similarly
during gestation
Abnormalties
 PSS
 Scrotal
Hernia- result from weak muscles
around the scrotum
 frequently
occurs at castration
 recessive gene action is probable cause
 Umbilical
busts
Hernia- belly ruptures or belly
Abnormalties

Atresia Ani- pigs born without an anus
 gilts
can survive, but boars die
Chriptorchidism- Males with one or both testicles
retained in the body cavity and the animal is sterile
 Hermaphrodites- intersexuality among European
breeds
 Underline defects - pin, inverted or blind nipples

Abnormalities
Tremors- shakers, trembles, myoclonia congenital,
shivers, jumpy pig disease
 Four types of tremors

 non-heritable:
caused by infection of certain hog
cholera strains and shows small brains and spinal cords
 non-heritable- pre-birth infection by a virus such as
PRV
 two type of heritable- recessive gene action with
specific breeds
Abnormalities
 Leg
defects:
 splayleg or spraddle legs- usually rear legs
affected
 truly
unknown, but causes considered are
choline deficiency, viral infection, etc.
 small
inside toes
 bent legs
Leg Defects cont.
 polydactyly-
mulefoot (presence of only one
toe per foot caused by single dominant
gene)
 thickened forelimbs- connective tissue
replaces muscle
 Non-leg defects:
 Blood Warts- moles or skin tumors
 Brain hernia- generally lethal
Abnormalities
 Humpback-
crooked spine
 Hemophilia (bleeders)- mycotoxins caused
and by recessive inheritance
 Rectal prolapse- no genetic influence (
caused by environ. such as coughing, piling,
feed ingredients, antibiotics and diarrhea)
Principles of Swine Breeding
and Selection
 Swine
testing programs
 production testing at central test stations or
on the farm
 Performance testing- testing of the
individual
 Progeny testing- testing of the offspring
 Pedigree selection- using the reputation or
records of animals for breeding selection
Possible economic important
traits for selection
 feed
efficiency
 litter size weaned
 % lean cuts or cutability
 conception rate
 21 day litter weight
 soundness score
 ave. daily gain
Types of Breeding
Crossbreeding: the mating of animals of different
breeds.
 Outcrossing: the mating of relatively unrelated
animals within the same breed.

Types of Breeding cont.
Inbreeding: production of offspring from parents
more closely related than the average of a
population.
 Line breeding: a form of inbreeding in which an
attempt is made to concentrate the inheritance of
some ancestor in the pedigree.

Principles of Swine Breeding
and Selection
 Breeding
Program- a designed system of
management to make genetic improvement
 Basic steps
 establish
goals
 determine economic traits
 utilize records
 evaluate performance
 stick to your program
Principles of Swine Breeding
and Selection
 Factors
that determine to include in a
selection program
 eonomic
value
 heritability
 genetic relationship with other traits
 ease of measuring
Heritability Estimate
 Heritability
estimate: hereditary variation
due to additive gene action.
 effects the rate of improvement
 low
heritability lends to slow rates of
improvement
 high heritability estimates yields faster rates of
improvement
Heritability Estimates for
economical important traits

Rate of Gain -days to
230

35%
 Feed Efficiency
 30%

15%
Loin eye Area
 50%
Ave. Daily Gain
 40%

Litter Weaning Wt.


Litter size



Carcass length


15%
60%
Backfat

40%
Terminology
 Prepotency:
the amount that an offspring
looks like the parent.
 Nicking: when genes of the dam and sire
complement each other.
 Heterosis: the improvement that the
offspring has over its parents.
Selection Systems
 Tandem-
looking at intensifying on one trait
at a time
 Independent Culling- using minimal criteria
to select for two or more economic
important traits
 Selection Index- using the combination of
two or more economic important traits by
observing an index to make selections for
breeding
Selection Differential
 definition-
the difference between animals
selected to be parents and the average of all
animals in the herd for selection for a
specific trait
 S. D. = ave. of animals selected minus the
ave. of all animals X heritability
Example of selection
differential for Feed
Efficiency
 selected
females - 2.9 and males at 3.1 # of
feed / # of gain
 ave. of parents = 3.0, herd ave. was 3.3
 diff. is .3, whereas heritablity = .35
 therefore, .3 X .35 = .105 gain from
selection
 $$$ ???? 40-240 # = 200 # gain = 600 # of
feed
Expected Progeny Differences
- EPD’s
a
prediction of the progeny performance of
an animal compared to the progeny of an
average animal in the population, based on
all information currently available.
 do not cross compare
 handout from Duroc Swine Registry
Swine Reproductive Anatomy &
Physiology
REPRODUCTION
DEFINITIONS
 Organ-
any part of the body having a
special function
 Gland- an organ that produces a specific
product
 Endocrine- a gland that secretes discharges
directly into the blood
 Exocrine- a gland which discharges its
secretions through a duct
Reproductive Function & Hormones in the
female are influenced in response to:
Lactation Length
Parity
Housing
Reproduction Depends Upon Hormonal
Interaction and Responses:
Hormone Concentration
Reproduction in Female
Pigs is Cyclic
70
60
50
40
30
20
10
0
Estrus
0
Estrus
Estrus
5 10 15 20 25 30 35 40 45 50 55 60 65
Day of Estrous Cycle
Estrogen
Progesterone
Estrous Cycle
The Hypothalamus
Secretes GnRH
(Gonadotropin Releasing Hormone) in
response to:
The Pituitary
Secretes gonadotropins in response to GnRH
FSH
Follicle Stimulating Hormone
LH
Luteinizing Hormone
Source of OXYTOCIN

(PG600 like)
Reproduction Depends Upon
Hormones:
Reproductive Hormones
Estrus
hormone concentration
70
LH Causes ovulation
Estrogen Induces estrus)
60
50
40
Progesterone
Prevents estrus
30
20
10
0
-6
-5
-4
-3
-2
-1
days before estrus
0
1
FSH
LH
Estrogen
Progesterone
Uterus
Oviduct
Ovary
Cervix
Bladder
Vagina
Vulva
Swine Female Repro Tract
The Vagina
The organ for copulation (mating)
pH unfavorable to sperm & microbes
The Cervix
Mucus source
has 5 interdigitating pads
protects fetus when closed
The Uterus
the site of embryo and fetal development
Prostaglandin production
prostaglandins
The Oviducts
catch egg
site of fertilization
leads to uterus
The Ovary
Has numerous follicles-
-which contain eggs & hormones
Embryonic Position in the
Uterine Horns
Reproductive Function & Hormones in the
boar are influenced in response to:
Housing
Hypothalamus Gland
Pituitary Gland
The Pituitary responds to
GnRH production
Testes
The testes respond to FSH & LH
presence by beginning
spermatogenesis.
Reproduction Depends Upon Hormonal
Interaction and Responses:
Male Hormone Production
The Hypothalamus
Secretes GnRH
(Gonadotropin Releasing Hormone) in
response to:
Boar Exposure –
Maturity Required

Boars should be
 Reasonably
aggressive
 Vocal
 Active
secondary sex
glands

sub maxillary salivary
glands

pheromones
MALE ANATOMY
 Testicles-
primary sex organ
 produces
sperm cells (spermatogenesis)
 Scrotum-
regulates temperature of the
testicles (tunical dartos muscle)
 Paniform plexus- network of arteries and
veins to provide blood supply of the
testicles
 located
cord
above the testicle within the spermatic
MALE ANATOMY
 Cryptorchidism-
one or both testicle that do
not descend into the scrotum during
embryonic development
 Epididymis- four functions for sperm cells
 transport
 storage
 maturation
 concentration
MALE ANATOMY
 Seminiferous
 place
 Vas
tubules- within the testicle
where sperm cells are formed
deferens - function is to transport
spermatozoa to the urethra
 Penis and urethra- transport spermatozoa to
the female for natural insemination
SEMEN
 Criteria
 motility
 percentage
 volume
of abnormal sperm
FEMALE ANATOMY
 Ovaries-
primary sex organ
 produces
the female reproductive cell “the egg”
 process of oogenesis
 unlike
the male, it is not continuous
 controlled by the estrus cycle
 produces
a primary follicle
 Graafian follicle: mature follicle
FEMALE ANATOMY
 Ovulation:
when the tissue ruptures and
releases the egg
 Corpus luteum- cells that grow rapidly
replacing the blood clot from the rupture
 plays
body
an integral role in pregnancy detection by the
FEMALE ANATOMY
 SECONDARY
 receives
SEX ORGANS
the semen and transports the sperm to
the egg
 infundibulum
 oviduct
(fallopian tube)
 uterine horns
 uterus
 cervix
 vagina
FEMALE ANATOMY
 Infundibulum-
catches the released egg
 Fallopian tube- place where fertilization
occurs

important that sperm is at the upper end when
ovulation takes place
 Uterine
Horns- where the embryo develops
in cattle, sheep, and swine before
attachment
FEMALE ANATOMY
 Uterus-
major body of storage for the fetus
 fetus
develops within the uterus within a layer
of membranes called the placenta
 Cervix-
overlapping and interlocking folds
that form the so-called neck of the uterus
 passageway
for sperm
 protection from infection during pregnancy
 Vagina-
receptacle for male for service
HORMONAL CONTROL
 MALE
 TESTOSTERONE responsible
secreted by the testicle
for development and maintenance of the
male reproductive tract
 sex drive
 increases muscular and skeletal growth
 essential for sperm formation
 development of secondary sex characteristics
HORMONAL CONTROL
 MALE
 Influenced
by the anterior lobe of the pituitary gland
 Gonadotrophic hormones that affect the male
 FSH (follicle stimulating hormone)

 LH

development of seminiferous tubules and sperm cells
(luteinizing hormone)
influences interstitual cells to secrete testosterone
HORMONAL CONTROL
 FEMALE
 Estradiol:
produced by the Graafian follicle
 Estrogen: a collective term for a number of
hormones similar to estradiol
 Functions:
 development
of secondary sex organs
 onset of estrus (heat cycle)
 affects rate and type of growth as well as deposition
of fat
HORMONAL CONTROL
 FEMALE
 PROGESTERONE
 hormone
of pregnancy
 suppresses production of follicles and estrogen
 prepares the uterus to receive the fertilized egg
HORMONAL CONTROL
 FEMALE
 HORMONES
 FSH-
stimulates growth of the follicle
 LH- causes rupture of the follicle
 LTH (lactogenic hormone)- milk secretion
 LH (luteotropic hormone)- formation and
maintenance of the corpus luteum (CL)
BREEDING AND
REPRODUCTION
 Reproduction
efficiency is most important
economic important trait
REPRODUCTION
 Puberty
4-7 months
 Gestation 114 days (3x3x3)
 Breed to farrow > than 1 year of age or
breed at least 225 lbs.
 Natural vs A. I.
 adv:
extension of semen, decrease disease
spreading
Heat Period
 Standing
Heat (2-3 days)
 Ovulations usually occurs 2nd day of heat
 swine should be bred at ovulation
 1st mating of gilts should be on the 1st day
 1st mating of sows should be on the 2nd day
 each should be re-bred 12 to 24 hours later
 cycle = 18 to 24 days ave. 21
Swine Fertility
 average
- releases 18-25 eggs
 fertilizes
14-18
 birth 8-14
 wean > 8
 Breed,
nutrition and disease dependent
Flushing the Sow
 increase
grain or concentrate in the diet
 two weeks prior to breeding
 increase eggs ovulated
 however, if over-conditioned, lightly
exercise gilts for 2-4 weeks before breeding
Breeding after farrowing
 standing
heat occurs 3-10 days after
weaning
 usually breed sows 2nd day after heat
detection
 commercial vs purebred
 breed 1st vs 2nd heat cycle
Reproduction Facts
 The
effect of increased dietary protein and
energy can increase gilt mammary tissue
slightly, coupled with lipid content in the
mammary glands
 Many cases of mature sows or just weaned
sows may deplete their Vit E reserves as
they age and while they are nursing
 High producing sows have higher nutrient
requirements
Repro Facts
 gilts
in confinement are slower to reach
puberty and show estrus
 keep gilts grouped together without
overcrowding
 provide exposure to boars for teasing
 replacement gilts are usually kept separate
at the end of the finishing floor and then
moved to the gestation barn at around 6.5
months of age
Repro Facts
 station
an old boar (because of stronger boar
smell) near the gilt pen
 Have a sprinkler system in the summertime
 Use lighting in confinement situations to
simulate outdoors
 Provide 16 hours of artificial lighting at 1/2
watt per sq. ft., esp. in the fall for breeding
More Repro Facts
 Yugoslavian
research indicates that sows
are safely pregnant after 42 days
 Therefore, it may help to continue to
provide boar exposure for 45 days postbreeding
 Any unusual change in the environment will
create estrus
 Poor ventilation - >20 ppm of ammonia will
decrease estrus
Don’t let them stop cycling
 seasonal
 feed
intake- not enough protein or energy
during lactation decreases estrus at weaning
 first litter sows are later than older sows
 feeding in gestation- too much can cause
more anestrous at weaning
 litter size ???? combined with nutrient req.
and feed intake
Detecting heat
 sows
ave. 5 days after weaning
 split weaning helps -wean half the litter 2
days before resulting sows in standing heat
sooner
 signs- swollen and reddening of the vulva,
mounting, etc.
 handout
Synchronizing Estrus
 PMS/HCG
(PG 600) ~ 75% effective for
gilts
 PMSG (Pregnant Mare Serum
Gonadotropin)- used to stimulate the
ovaries to develop eggs - follicular growth
and development (heat)
 HCG (Human chorionic gonadotropin) cause follicles to rupture
 ovulation usually occurs within 40-42 hours
In Synch
 show
heat 3-5 days after injection
 90% come into heat
 PG 600 is used to stimulate follicular
growth, heat and ovulation in gilts with
inactive ovaries
 not recommended always, but used for gilts
Synching more
 Prostaglandins-
causes the regression of the
CL (corpus luteum) for controlling
farrowing, but not synchronizing (only
causes regression of CL that have been
present in pregnant or non-pregnant animals
for at least 12-14 days)
Synching further
 Oxytocin
- induces uterine contractions
(smooth muscle contractions)
 Altrenogest (Regumate)- not commercially
approved as of early to mid 1990’s. Used to
stop follicular development. Can be mixed
in with the feed.
More Drugs
 Lutalyse
for sows only if accurate records
are kept
 inject not more than 2 days prior to
farrowing date and should see farrowing
within 36 hours after injection (92% from
one study of 38 sows)
 Use the herd average as a base
 Ex. if the herd ave. is 115 days then give it
on day 113
More on Drugs
 add
oxytocin to Lutalyse ~24 hours after
lutalyse injection
 lower numbers for number born alive
 yet with Lut. and Oxyt. + attendance
numbers came back to the control or
Lutalyse
 Another study observed 129 sows using .5
mg Lutalyse, Bovilene (another
prostaglandin), or nothing
Much More on Drugs
 Only
26% farrowed for the control group
within 36 hours
 Bovilene affected 98% and Lutalyse caused
76% to farrow within 36 hours
 Ave. interval from injection was 25 hrs. for
Bovilene and 26 hours for Lutalyse and 58
hours for the control group
 Lutalyse sows were more restless than the
other two groups
Repro Facts-Vit E
 They
will pass on Vit E to the baby pigs if
they have it in their diet, espec. in the
colostrum
 In a study at Ohio State, Sows need at least
15,000 IU/ton for proper efficiency
 When compared to 0, 30K, & 60K IU/ton,
sows performed at 1-1.2 pigs more/ litter at
birth and .8-1.2 at 7 days after farrowing
Repro Facts-Vit E
 MMA
and pig mortality decreased with
increased Vit E > 15K IU/ton
 Also, secondary problems such as sudden
death syndrome, diarrhea, spraddle-legs,
increased stillborns, gut edema, and poor
performance were decreased with an
increase of Vit E
 Available in both feed and injection
Natural vs AI
 More
sows bred per boar with AI
 Usually extend semen to 5-8 sows instead
of 1 sow with Natural mating
 A combination in commercial operations
has shown to increase performance and
reduce labor
 Recommended to breed naturally the first
day and AI on the second day of breeding
Mating Frequency for gilts
 Mating
frequency does not affect pregnancy
for one-day estrus groups
 However, those longer than 3 days are
problems
 Those exhibiting 2 day estrus showed
greater litter sizes for double breeding (a
AM and PM breeding for that day)
Mating Frequency cont.
 Litter
size improved for those bred two to
four times, but did not improve pregnancy
rates
 In general, as mating freq. increases, reprod
performance increases
 onset, timing, and duration of ovulation
varies considerably with gilts
Feeding and litter size
 flushing
increases litter sizes for gilts, yet
not necessarily for sows
 usually at least one pig per litter when
flushed
 However, it is recommended not to flush
gilts if they are currently in standing heat
 Wait till they complete estrus, then start
flushing
Feeding and litter size
 when
feeding high fiber within the gestation
ration sow weight gains and pig
birthweights are not negatively affected,
except for extremely high fiber diets
 when fed 96% fiber, sow did not gain much
and had .5 lbs per pig less at birth
 when fed 20-40% fiber, no real affect was
seen as compared to a corn-soybean diet
Feeding and Repro
 gestation
and lactation rations (14% CP)
 Fungus on milo or Mold on Corn can
reduce fertility
 increase Ca:P and energy for lactation
 don’t overfeed (embryonic death)
Heat Stress
 an
added 2-3 degrees F can cut sperm
production in herd boars
 > 95 F for two days will reduce sperm
counts for as long as 60 days
 for growing-finishing pigs, turn sprinklers
on >80 F
 shade vs. sprinkler vs. air-conditioning