Brainscape's Knowledge GenomeTM


Top Flashcards (Certified)
All Flashcards

VET 410: Reproduction > Bovine Cyclicity > Flashcards

Bovine Cyclicity Flashcards

1
Q

are cows seasonal or nonseasonal

A

nonseasonally polyestrous

cycle every 21 days

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
2
Q

is anestrus normal in a cow

A

NO unless:
- pregnant
- prepubertal
- suckling

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
3
Q

is luteolysis in cows spontaneous or gradual/senescent

A

spontaneous
can shorten luteal phase if pregnancy is not established via uterine prostaglandins

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
4
Q

how long is the follicular phase in cows

A

SHORT (2-3 days)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
5
Q

what are signs of estrus in cows

A

stands to be mounted
clear secretions from vulva
increased uterine tone

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
6
Q

when does ovulation occur

A

12 hours AFTER estrus ends

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
7
Q

when does luteinization occur

A

AFTER ovulation

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
8
Q

what are the stages of the bovine cycle

A
  1. proestrus
  2. estrus
  3. metestrus
  4. diestrus

NO anestrus unless pregnant/prepubertal/suckling

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
9
Q

proestrus

A

mounting/chasing other females

short - 12-24 hours

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
10
Q

estrus

A

stands to be mounted, clear secretions from vulva

short - 12-24 hours

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
11
Q

metestrus

A

period of CL formation that occurs after ovulation

bloody discharge from vulva

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
12
Q

diestrus

A

luteal phase

long - 19-20 days

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
13
Q

is follicular development from primordial to tertiary follicles FSH dependent or independent

A

FSH independent - follicles can grow prior to puberty but oocyte will NOT ovulate

follicles will undergo atresia

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
14
Q

is follicular development from tertiary to Graafian follicles FSH dependent or independent

A

FSH dependent - can only occur after puberty

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
15
Q

how many oocytes ovulate per cycle

A

1-2

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
16
Q

do cows ovulate a primary or secondary oocyte

A

secondary oocyte - can get fertilized immediately after ovulation to induce the resumption of meiosis

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
17
Q

do follicules get recruited throughout the cycle or only during follicular phase

A

follicles get recruited in waves throughout the cycle

if recruited during luteal phase: undergoes atresia due to high progesterone

if recruited during follicular phase: 1 will ovulate (progesterone is low)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
18
Q

progesterone and estradiol levels during estrus/ovulation

A

HIGH estrus
LOW progesterone

unlike dogs - do NOT need progesterone to trigger estrus

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
19
Q

is the LH surge long or short

A

SHORT and sharp - ovulation is rapid and occurs 12 hours after estrus

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
20
Q

is there an FSH surge along with LH surge in response to GnRH

A

NO because growing follicles also release inhibin B - negative feedback on FSH prevents FSH surge

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
21
Q

post ovulatory luteinization

A

LH surge stimulates granulosa cells to express LH receptors –> starts secreting progesterone

occurs AFTER ovulation due to rapid estrus and ovulation

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
22
Q

what hormone is responsible for inducing spontaneous luteolysis

A

prostaglandin F2a (PGF2a)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
23
Q

spontaneous luteolysis in cows

A

at the end of the luteal phase, if no fertilization:
- ipsilateral uterine horn releases PGF2a
- PGF2a travels in uterine vein then diffuses into ovarian artery
- PGF2a travels back to the ipsilateral ovary
- induces regression of the CL

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
24
Q

can local induction of luteolysis occur in other species besides cows

A

NO because the vascular architecture allows the UV and OA to be closely related for PGF2a to diffuse across easily

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
25
can PGF2a released from one uterine horn affect the contralateral ovary in cows
NO because PGF2a that enters systemic circulation gets metabolized in the lung (pulmonary epithelium) insufficient amounts make it back to the contralateral ovary - not enough to induce luteolysis
26
what is the +/+ feedback loop of OT and PGF2a
corpus luteum will produce OT to aid in inducing luteolysis 1. CL produces OT 2. OT binds receptors on endometrium 3. stimulates PGF2a release from uterus 4. PGF2a travels from UV to OA back to the ipsilateral ovary 5. induces luteolysis of the CL
27
superovulation
exogenous administration of FSH during the luteal phase can "rescue" follicles that would otherwise become atretic FSH will NOT stimulate follicle growth, only rescue existing follicles from atresia
28
AM/PM rule of cows
when cows are in heat in the morning, inseminate them in the evening (12 hours later) and vice versa because ovulation occurs 12 hours post-heat want sperm present at time of ovulation because secondary oocytes have a short lifespan once ovulated and sperm has short lifespan in female repro tract
29
cycle synchronization/shortening
exogenous PGF2a can be administered 5-6 days after ovulation to shorten the cycle and synchronize the herd must be administered once CL is fully formed and responsive to PGF2a (5-6 days)
30
what hormone prepares the endometrium for pregnancy during early luteal phase
progesterone stimulates endometrial secretions in order to synchronize embryonic and endometrial development (ensures adequate environment for embryo to grow)
31
days/events of embryonic development
day 1 to 4/5: embryo develops in oviduct day 5: enters uterus day 12: elongates to fill uterine horn day 17: MRP
32
maternal recognition of pregnancy
physiologic prevention of luteolysis resulting from embryonic secretion of interferon tau
33
why does luteolysis need to be prevented in order to maintain pregnancy
progesterone is necessary to allow for coordinated/synchronized embryonic and endometrial development composition of uterine secretions changes throughout pregnancy - need progesterone to control secretions
34
interferon tau
secreted by the embryo prior to luteolysis downregulates OT receptors to prevent the +/+ feedback loop of OT and PGF2a - decreased stimulation of PGF2a allows CL to persist - persistent CL continues secreting progesterone
35
is MRP local or systemic in cows
local due to vascular architecture embryo will prevent PGF2a secretion from the IPSILATERAL horn only - will not be affected by PGF2a from the contralateral horn
36
does MRP occur in carnivores
NO because luteolysis is not spontaneous in carnivores
37
when is the fetus able to start developing
once the placenta is formed (day 40) required to allow for the exchange of nutrients and waste
38
at what part of gestation does the majority of fetal development occur
last 1/3 of gestation
39
is the placenta able to produce progesterone in cows
yes after day 150 CL is NOT needed from day 150-240 (is needed again from 240-280; unknown why)
40
what are early signs of pregnancy on rectal palpation
1. amniotic vesicle in ipsilateral horn (day 35-60) 2. membrane slip (intercaruncular spaces; day 42+)
41
what are later signs of pregnancy on rectal palpation
1. fetus (day 65+) 2. caruncles (day 90+) 3. fremitus (day 150)
42
fremitus
turbulent blood flow in the uterine artery causing a "fluid thrill"
43
what 3 ways are used to diagnose pregnancy in cows
1. rectal palpation - day 35 earliest 2. ultrasound - day 28 earliest 3. pregnancy specific protein B - day 24 earliest
44
progesterone withdrawal
the drop in progesterone that occur within a few days of parturition to initiate fetal expulsion
45
fetal HPA axis
increases in fetal cortisol secretion prior to parturition induces an increase in placental estradiol and endometrial PGF2a secretion to initiate parturition
46
pre partum surge of PGF2a
fetal cortisol --> surge of PGF2a --> rapid luteolysis/CL regression --> decreased progesterone
47
effects of high estradiol and low progesterone at parturition
- induces cervical relaxation - increases myometrial membrane potential - increases oxytocin receptors - increases gap junctions
48
what hormones can be administered exogenously to induce abortion/early parturition
PGF2a or dexamethasone (depends on timeline) PGF2a alone: works during months 1-5 and 7-9 dex alone: works during months 7-9 PGF2a + dex: works during months 5-7
49
Ferguson reflex
neuroendocrine reflex triggered by cervical stretch receptors resulting in OT secretion oxytocin stimulates: - myometrial contractions - +/+ feedback with PGF2a
50
tocolytics
administration of B adrenergic agonists to delay parturition for a SHORT period of time increases cAMP in smooth muscle --> decreases Ca --> decreases uterine contraction
51
BOVINE THING 1: are cows seasonal and do they experience anestrus
non-seasonal - cycle year round anestrus is abnormal unless pregnant, prepubertal, or suckling
52
BOVINE THING 2: is estrus long or short
SHORT (<24 hrs)
53
BOVINE THING 3: when does ovulation occur
ovulation occurs 12 hours after estrus ENDS AM/PM rule
54
BOVINE THING 4: how long do sperm remain viable in the repro tract
SHORT - especially if not fresh (AI)
55
BOVINE THING 5: what allows super ovulation to occur in cows
follicles emerge in waves throughout enter cycle (including luteal phase) super ovulation uses FSH to "rescue" the follicles released during luteal phase
56
BOVINE THING 6: is luteolysis local or systemic
local - uterine PGF2a only reaches the ipsilateral ovary due to vascular architecture of the uterine vein and ovarian artery
57
BOVINE THING 7: what hormone stimulates uterine PGF2a to initiate luteolysis
oxytocin secreted from the corpus luteum (+/+ feedback)
58
BOVINE THING 8: is MRP local or systemic
local - interferon tau secreted from the embryo suppresses PGF2a secretion from the ipsilateral uterine horn
59
BOVINE THING 9: how is pregnancy maintained after day 150
placental progesterone can support until day 240 (still need CL past then)
60
BOVINE THING 10: what initiates parturition
luteolysis - induced by stimulation of fetal HPA axis --> high cortisol --> high PGF2a from endometrium

VET 410: Reproduction (24 decks)

Brainscape helps you reach your goals faster, through stronger study habits.
© 2025 Bold Learning Solutions. Terms and Conditions