Swine reproduction Flashcards
What type of structures do sows have in their cervix?
interdigitating prominances
It contains a series of five interdigitating pads which provide pressure points for locking of the penis (or AI catheters).
Where does fertilization take place in the sow?
in the mid portion of the fallopian tube/oviduct, called the ampulla
The fimbria wraps around the entire ovary, and under the influence of estrogen, induces muscular contractions which propel all of the eggs into the funnel shaped opening of the oviduct.
In sows, the bladder empties into the vagina on the floor of the vagina approximately 5 cm from the external opening.
This is important because?
Many types of spiral AI catheters can mistakenly be inserted into the urethral opening of the bladder instead of the cervix.
The pig vulva is endowed with blood vessels and ican be observed to swell and change in color near the time of estrus. What type of pig is this evident in and in which type is it not?
In gilts, is evident. This swelling and color change are not as evident in sows, and color changes are not observable in dark skinned pigs.
Replacement gilts are chosen based on: (6)
Reproductive performance of dam and sire
Sows farrowing nr
Sows age of puberty
Birth weight
Season of birth
Weight at weaning
Gilts reach puberty at how many days old?
Which breeds earlier and which later?
150 – 250 days (mean = 200 days)
Cross Breeds< Landrace< Yorkshire < Durocs
Earlier in Boar
Gilts coming in to puberty Can be Delayed/Hastened by # of Factors such as: (6)
Inbreeding
nutrition
confinement
lighting
boar exposure
season of birth (winter < spring)
Growing follicles consist of… (3)
an oocyte with 2 or more layers of granulosa cells and a basement membrane.
Until puberty, they will only develop to the stage where they have a theca interna and then start to undergo atresia.
Gilt follicles begin to react to gonadotropins at what age?
the 70th day after birth so ca 2-3 months
Factors affecting activation of LH surge in gilts. (2)
Threshold (high in prepubertal period) for the positive-feedback effect of estradiol.
Gonadotropin-releasing hormone (GnRN) from the hypothalamus.
How does gilt group size seem to affect onset of puberty?
How does exposure to boar seem to affect onset of puberty?
exposure = accelerated puberty
What type of breeders are sows?
Non-seasonal polycyclic
Length of sow estrous cycle?
Duration of sow estrus?
Length of estrous cycle 21 days
Duration of estrus 2-3 days
Ovulation during the last day of estrus (24-42 h) (back pressure test).
When exactly do sows ovulate in relation to estrus?
Ovulation during the last day of estrus (24-42 h) (back pressure test).
The time of ovulation after onset of estrus is highly variable between females (24 - 60 h after onset of estrus).
Name & describe the sow’s estrus cycle stages. (4)
pro, estrus, met, di
Proestrus 1-3 days
* The phase immediately preceding estrus. Alert to boar but will not accept.
Estrus 3-4 days
* Physical and behavioral signs. Ovulation occurs mid-late estrus.
Metestrus 2 days
* The phase succeeding estrus
Diestrus 14 days
* The period of CL
Name 3 environmental factors to affect sow cyclicity:
Light (10–14 h)
Nutrition (flushing)
Temperature
What is the point of Artificial control of cyclical reproductive activity in pigs?
To Control the average age of first estrus in gilts.
Its possible to activate the cycle in gilts 1-2 months before the average age of first estrus.
Gilts that are too young or that weigh less than 85 kg may not be mature enough to continue normal estrus cycles or maintain a normal pregnancy to full term after treatment.
Hormonal methods of synchronization
Combination preparation of hCG and eCG mimics naturally occurring reproductive hormones, FSH and LH.
These stimulate estrus in adult sows within 4-5 days.
And they stimulate induction of cyclicity in gilts within 28 days of tx.
Optimal time of insemination in gilts, and weight?
In sows?
Gilts ≥ 120 kg, 210 days old.
Optimal AI/mating time in Gilts is immediately after detection of „standing estrus“ and rebreeding – 12 h later.
Sows: 4-7 days after weaning.
Optimal AI/mating time in sows is 12 h after detection of „standing estrus“.
Control of BCS during anoestrus.
However, since length of estrus, and time of ovulation after onset of estrus are variable we bred for the potential of both and early and late ovulation, by using two inseminations 12 to 24 h apart
In sow insemination, Sperm are typically deposited into
the reproductive tract near the junction of the cervix and uterus.
Although much of the inseminate enters the uterus, there is a significant back-flow loss of semen volume which occurs over the next several hours after insemination.
Under stimulation from uterine contractions induced by both oxytocin from the female and prostaglandins in the semen of the boar, sperm are moved to the site of fertilization.
In the pig the biological potency of porcine FSH is greater than
bovine FSH and it seems that porcine FSH secretory cells are less sensitive to inhibin.
This means that when smaller bovine follicles become atretic due competition with the most mmature follicle - in pigs, the more mature follicles actually assist the development of the less mature follicles.
The pig develops hundreds of small follicles during an estrous cycle, but typically only ovulates between 10-20 of these follicles.
Sometimes follicles develop to a large size but fail to ovulate, leading to the condition known as
cystic ovary disease.
Cystic ovaries:
Multiple large cysts (< 14 mm), produce progesterone.
Multiple small cysts, produce estrogens.
Single cysts, rarely affect sow fertility.
Some sperm cells reach the site of fertilization within minutes after insemination, however, these sperm cells are incapable of fertilizing eggs because?
a time dependent passage through the female uterus is required to prepare them to attach to the egg (Sperm capacitation).
Most of the fertilizing sperm will reach the egg in about 3-6 h after insemination, but numbers of sperm will continue to increase in the oviduct for up to about 12 h after insemination.
Once fertilization does occur, early embryos develop in the oviduct for how long before they leave?
~48 h until they leave the oviduct.
Eggs that are not fertilized usually pass into the uterus within several days.
The early conceptus reaches the uterus how many hours after fertilisation as a morula?
What day is it a Blastocyst?
On what day are the embryos large spheres 9-10mm?
On what day are the embryos tubular?
On what day are the embryos filamentous?
Reaches the uterus at 60-72 h after fertilisation – morula.
Blastocyst – 5th day
11th day – large spheres 9-10mm
13th day – tubulars 33 cm long
16th day –filamentous 0,7-1m long, Ø 0.5 – 1 mm
The most critical time for the sow embryo is from days…?
day 11-12
Embryonic attachment to the uterus from the 14th day.
What type of placenta do pigs have?
True epitheliochorialdiffuse
placenta
Maternal recognition of pregnancy in sows. (4)
Series of complex biochemical and cellular interactions.
Trophectoderm secretes:
* estrogens (catecholestrogens, estrone and estradiol),
* interferon gamma (IFNG) and
* interferon delta (IFND) and
* interleukin 1 beta.
Role of estrogens in recognition of sow pregnancy. (3)
The secretion of oestrogen stimulates the release of calcium, specific polypeptides and proteins needed for establishment of pregnancy.
Plus a role in extension of the CL lifespan.
Estrogens stimulate luteal progesterone secretion directly.
They also inhibit release of PGF2α.
Causes of embryonic/fetal loss. (6)
Environmental factors
Infections
Nutrition
Stress
Ovulation rate, uterine and hormonal factors
Genetic causes
Infectious causes of embryonic/fetal loss in pigs. (8)
Parvovirus
Leptospira spp.
PCV2
Erysipelothrix rhusiopathiae
Listeria monocytogenes
E. coli
Mycoplasma spp.
Streptococcus spp.
