Bovine - Pregnancy and Parturition Flashcards
How long does standing estrus last?
12-18 hours
When does ovulation occur in relation to standing estrus?
10-16 hours after the end of standing estrus
How long does it take from the start of estrus to ovulation?
30 hours
When does insemination occur in relation to estrus/ovulation?
it occurs during estrus so that semen is present at the time of ovulation for fertilization (ampulla)
What is the viability of fresh semen?
36-48 hours
What is the viability of frozen semen?
12-24 hours (conventional) or 8 hours (sexed)
What is a sperm reservoir in a cow?
Sperm attaches to the wall of the oviduct, slows down their metabolic activity until there is a chemical response that reactivates them, then they unattach and move to the ampulla
What occurs here (1)?
retrograde loss, phagocytosis, entrance into cervix/uterus
What occurs here (2)?
privelaged pathways’, removal of non-motile sperm, removal of some abnormalities
What occurs here (3)?
capacitation initiated, phagocytosis
What occurs here (4)?
capacitation completed, hyperactive motility
What occurs here (5)?
acrosome reaction, spermatozoon penetrates oocyte, male and female pronuclei form
When must maternal recognition occur?
prior to luteolysis
What is needed to allow changes in the endometrium to support pregnancy?
progesterone
What is Interferon-T?
a signaling molecule
What is interferon-T produced by?
trophoblastic cells from the embryo
What does interferon-T do?
it blocks the release of prostaglandin from the endometrium - blocks oxytocin receptor
What cellular layer makes the placenta?
the trophoblasts cellular layer
When, during pregnancy, does attachment of the embryo begin and when is it completed?
it starts at day 20 and is completed by day 40
What type of placenta do cattle have?
cotyledonary
How many layers are in between the fetus and the dam in cattle?
6 layers - syndesmochorial
What are the parts of the placenta?
amnion, allantois, and chorion
How is pregnancy diagnosed in cattle?
rectal palpation, ultrasound, and blood tests (expensive)
What are the cardinal signs via rectal palpation of pregnancy?
fetus, amniotic vesicle, membrane slip, and placentomes
What are the advantages to doing ultrasound for pregancy testing?
fetal viability, fetal sexing, better twin diagnosis, and pathology
What hormone is needed throughout pregnancy?
progesterone
What provides the primary source of progesterone for the first 5 months of pregnancy?
the corpus luteum
What provides progesterone from 6-8 months?
the placenta
What provides progesterone in the last month of pregnancy?
the corpus luteum
A.
fetal cortisol
B.
placental P4
C.
E2
D.
increased secretion by reproductive tract
E.
lubrication
F.
increase in myometrial contractions
G.
increase in pressure
H.
increase in cervical stimulation
I.
Increase in oxytocin
J.
Maximum pressure
K.
PGF2-alpha
L.
Luteolysis
M.
Relaxin
N.
Pelvic ligament stretching
What is the function of progesterone during pregnancy?
to inhibit or block myometrial activity (uterine quiescence)
What causes the initiation of myometrial contractions?
removal of progesterone block by conversion of progesterone to estrogen by fetal cortisol - also allows PGF to be releaseed to aid in parturition
What initiates stage 1 of parturition?
the fetus
What occurs during stage 1 of parturition?
myometrial contractions and cerviccal dilation - prepares the fetus for delivery
How long does stage 1 of parturition typically take?
2-6 hours
What are the typical signs associated with stage 1 parturition?
separating from the herd (prey animals), mild contractions and moving around (up and down), and pelvic ligaments relax (relaxin)
What occurs during stage 2 of parturition?
fetal expulsion - straining and strong contractions (ferguson reflex), breaking allantois, and breaking amnion
How long does fetal expulsion typically take in cows? Heifers?
cows - 30-60 minutes, heifers - 2 hours
What occurs during stage 3 of parturition?
fetal membrane expulsion
How long does fetal membrane expulson typically take?
6-12 hours
When should you consider that there is a retained fetal membrane?
after 12 hours
What must happen in order for the fetal membrane to be dislodged?
chorionic villi must dislodge from crypts on the endometrium (caruncles)
When would you want to induce parturition?
mismating or to induce it prior to the due date
What can you give prior to 150 days of pregnancy to induce parturition?
PGF
What can you give after 150 days of pregnancy to induce parturition?
dexamethasone and PGF
When trying to induce a viable calf early, what exogenous drugs can be used?
PGF, dexamethasone, or PGF and dexamethasone
What role does dexamethasone play when inducing parturition?
mimic fetal cortisol
