Lecture 15 & 16: Bovine Patterns (Galvao) Flashcards
what suspends the uterine tube (aka oviduct)?
the mesosalpinx - which is a portion of the broad ligament.
*note: oviduct is considered an old term according to Galavao and he will be referring to the oviduct as “uterine tube.”
what connects the ovaries to the pelvic or abdominal wall?
a fold of peritoneum called the mesovarium.
what suspends the uterus?
a portion of the broad ligament known as the mesometrium
what is the function of the infundibulum and fimbriae?
they catch the oocyte after ovulation.
what type of estrous cycle does the cow have?
polyestrus!
what is the gestation of the cow?
280 days
what does standing behavior in the cow indicate?
ovulation occurs in 24 hours
what is the source of progesterone in the cow?
progesterone comes from CL UNTIL day 150. after that the placenta takes over.
how many follicular waves does the cow have before ovulation?
usually 2. a heifer (first time mom) may have 3.
how many follicles ovulate in the cow?
just one. they may have co-dominant follicles but only one ovulates.
how many phases are there to the ruminant cycle and what are they?
there are 4:
- proestrus
- estrus
- metestrus
- diestrus
what is the duration of proestrus in the cow? what happens during this phase?
2- 3 days
the CL regresses (progesterone levels plummet) and the current dominant follicle grows (estrogen levels rise).
the uterus becomes edematous and tone increases.
what is the duration of estrus in the cow? what happens during this phase?
estrus = 12 - 18 hours
- estrogen levels peak, followed by a preovulatory spike of LH which triggers ovulation 24 - 30 hours later, AFTER the end of heat.
what are behavioral signs of estrus in the cow?
primary sign is standing to be mounted.
secondary signs - restlessness, mucous discharge, depressed milk production
when is the optimal time for insemination in the cow?
near the end of standing heat
what is the duration of metestrus in the cow? what happens during metestrus?
4 days
- its the period during which ovulation occurs (in the oviduct).
- the cow is the only domestic animal that ovulates AFTER the END of estrus**
- it is the period of corpus hemorrhagicum and increasing progesterone levels.
- follicular cells develop into luteal cells.
what is the duration of diestrus in the cow? and what happens during this phase?
14 days
- the CL is mature and therefore progesterone dominates.
- there are small peaks of FSH on days 4, 8, and 12 in concert with follicular growth. each wave produces a dominant follicle but ovulation does not occur b/c of high progesterone.
what causes CL regression?
endogenous PGF2-alpha release on day 18 of the cycle.
what causes a follicle to become dominant?
- it has developed thecal and granulosa cells which produce testosterone and estrogen
- the follicle uses estradiol which has a negative feedback on FSH which is what induces follicular waves.
- it produces inhibin which inhibits the growth of other follicles.
what happens to dominant follicles that cannot ovulate?
they become atretic (undergo apoptosis)
what triggers ovulation?
LH SURGE!!!
what triggers the LH surge?
this is something we MUST know!
estradiol.
* it has a positive feedback on LH under low progesterone levels.*
where does prostaglandin get released from in cows?
the uterus - specifically the same side as ovulation.
where does fertilization occur in cows?
in the uterine tube aka oviduct
how does luteolysis (regression of the CL) take place?
prostaglandin (PGF2-alpha) is drained from the endometrium from uterine veins. the uterine veins travel next to the ovarian artery and through countercurrent exchange, prostaglandin is picked up by the ovarian artery and taken to the ovary.
what day is prostaglandin produced by the uterus?
day 15 - 17 (says 18 in SCAVMA notes)
how long does it take after initial release of prostaglandin until you get complete luteolysis?
36-48 hours
ewe is….
a female sheep
doe is….
a goat. a female goat.
julie andrews got it wrong :-P
characteristics of cervix in a ewe
has 4 to 6 cervical rings, torturous (AI is more difficult)
describe cervical anatomy in the doe
4 to 6 cervical rings, are more aligned.
what is the reproductive activity in caprine and ovine?
regulated by seasonal variation - changes in day length or photoperiod (like the horse)
are cows seasonal breeders?
NO! they breed throughout the yearr
are caprine and ovines long or short day breeders?
short! this means they cycle during the fall and winter when there are low levels of light)
(this is the opposite of the horse - they are long day breeders and cycle during the spring and summer when photoperiods are longest)
where does source of progesterone come from during pregnancy in the ewe and ovine?
from the CL for the first 54 days but after that fetal placenta takes over
when does an embryo become a fetus?
once organogenesis is complete. in cows, this happens around day 40 in gestation.
how long does the embryo remain in the oviduct for in ruminants?
about 4 days
when is pregnancy recognized in ruminants?
on days 15 - 17
what prevents luteolysis in the cow?
a conceptus protein called bovine interferon tau (bINFt)
what controls the duration of gestation in ruminants?
the fetal pituitary - adrenal axis
~ 283 - 292 days
where does capacitation occur and how long does it take?
occurs in the oviduct and takes about 10 hours
when do you inseminate the cow if she is going to ovulate in 24 hours?
10 hours before ovulation, because the lifespan of an oocyte is 10 hours and it takes about 10 hours for capacitation to occur.
where does fertilization occur in ruminants. Be specific! :-P
the AMPULLA of the oviduct
what is the maternal recognition of pregnancy?
blastocyst produces IFN-tau hormone which blocks oxytocin receptors which inhibits luteolysis.
(oxytocin is needed for luteolysis to occur)
where is oxytocin released from?
the POSTERIOR pituitary
what is the placentation of ruminants?
epitheliochorial, cotyledonary, nondeciduous
when does implantation occur in cows?
28 - 33 days
when do placentomes develop?
~ 40 - 45 days
what hormonal changes take place during parturition in ruminants? what does it lead to?
they follow a sequence of increasing fetal cortisol concentrations, increased fetal placental estrogen concentrations and decreasing progesterone concentrations.
- this leads to increased myometrial contractility and responsiveness to oxytocin.
what hormone is released from ovaries just before labor and parturition?
relaxin
Stage 1 of labor in ruminants: how long does it last? what happens physiologically? are there signs?
2 - 6 hours
- uterus makes small contractions, cervix dilates
- may sometimes see isolation, restlessness, tail raised. but sometimes will notice nothing.
what happens at the end of stage I and beginning of stage 2 in ruminants?
- uterine membranes appear!
1st choriallantoic: watery brown or yellow liquid
2nd amniotic: usually this is what is seen - thick, clear-white fluid
average interval between rupture of 1st and 2nd = 15 minutes
Stage 2 in ruminants - what happens?
active abdominal contractions. calf enters birth canal.
- cow continues to dilate and calf is born
- usually lasts between 15 to 90 minutes but may last up to 6 hours
Stage III in ruminant - what happens?
expulsion of fetal membranes.
should take between 2 - 8 hours.
- considered retained if takes between 12-24 hours.
