Lecture 2: Bovine Infertility (Risco) Flashcards
infertility = sterility ?
NO.
T/F: infertility is a sign, not a specific condition
T
T/F: there are both infectious and non-infectious causes of infertility
T
estrus vs. estrous
estrus: a noun “a cow displays estrus”
estrous: an adj. “the estrous cycle”
most common form of infertility
non-infectious (esp. due to lack of detection of estrus)
main causes of non-infectious infertility
cow is in anestrus due to failure to detect estrus** or failure to exhibit estrus. If the latter occurs, the cow is in true anestrus and something is likely actually wrong with the cow.
1ary sign of estrus
standing to be mounted
methods to help improve detection of estrus
- heat detection aids
- synchronization of estrus or ovulation (i.e. using Ovsynch protocol or PGF2a)
Heat detection aids
- Pressure activated device
- Tail chalks/paints
- Pressure detector (heatwatch) -detects when cow being mounted
- Activity monitoring systems (accelerometer, pedometer, collar)
detection of cows displaying estrus (AI submission rate) determines:
when cows are first bred at the end of the VWP
activity monitors measure:
- activity
- laying bouts
- laying time
- rumination
example of a heat detection aid
HeatWatch II system. When cow mounts another cow, it triggers a sensor which alerts a computer of the event
Ovsynch TAI Protocol
(ovulation occurs before d0) d0: give GnRH d7: give prostaglandin d9: give GnRH d10 (16 hours post-GnRH): TAI (Timed Artificial Insemination)
How to synchronize estrus for AI (not Ovsync)
d0: give PG
d14: give PG again
d16-21: AI
Describe how Progesterone (P4) lvls change throughout OvSync protocol
At ovulation (before d0), progesterone starts at a very low level then steadily increases before plateauing around 7 ng/ml just before d0, when GnRH is given. Plateau continues until d7, when PG is given. P4 then drops off to a negligible level around d8.5. GnRH given again at d9 and then TAI started at d10. (See slide 15)
When do follicular waves occur in Ovsync?
First wave starts at ovulation when P4 is increasing before d0. Second wave starts around d2-3 and ends after d10 when TAI is occuring.
Presynch-Ovsynch protocol
d0: PGF
d14: PGF
d26: GnRH
d33: PGF
d35: GnRH
d36: TAI
anestrus =
failure to exhibit estrus
causes of anestrus**
poor nutrition, neg. energy balance, debilitating dz cystic ovaries or tumors endometritis/pyometra congenital defect pregnancy heat stress rBST (bovine somatotropin)
peak milk production occurs how many weeks post-partum?
4
When does peak dry matter/energy intake occur?
6-8 weeks post-partum
where does most energy for peak milk production come from?
mobilized fat (lose BC as a result)
most cows lose how many BCS post-partum?
1
When does cow return to positive energy balance post-partum?
8 weeks post-partum (when dry matter intake is peaking)
what does neg. energy balance disrupt?
hypothalamic pituitary axis. Pushes cow nearer to ketotic.
- glucose low
- free fatty acids high
- ketone bodies high
nadir
lowest point in negative energy balance
SEE SLIDE 19
:)
GnRH secreted by:
hypothalamus
increased insulin –> response to LH
increases
inc. response to LH –> estradiol (E2)
inc.
describe LH pulses before and after NADIR. Why?
before: low and infrequent
after: higher and more frequent because there is more GnRH and FSH coming from the pituitary and cow will then ovulate
cow will only ovulate past the ___ of NEB
nadir
in well managed herds, ovulation can reach what percentage?
80-90% (those that fail to ovulate still have some NEB and must wait to ovulate until they peak their DM intake)
average fate of dominant follicle of first wave
ovulate: 50% don't ovulate: 25% becomes cystic (follicular or luteal): 25%
follicular cyst
follicle that fails to ovulate because there isn’t enough LH
-produces NO progesterone
luteal cyst
forms because there was only enough LH to cause a PARTIAL ovulation.
-surrounded in basement membrane (luteal tissue)
which species are more prone to cysts?
cats, cow, horses
which cyst is more common: follicular or luteal?***
luteal
What is a CL?
a follicle that fails to ovulate. Does not form corpus hemorrhagicum
Does luteal cyst produce progesterone?
Yes (but only some). Progesterone that is produced keeps cow in estrus
When is there no tonicity in the uterus?
during proestrus and estrus
If you feel no CL and large follicular degeneration, could be:
cow could be coming into estrus, OR may be follicular cyst
CS of cystic follicular degeneration
- frequent estrus
- irregular estrouscycles
- anestrus
Dx of cystic follicular degeneration based on:
- anovulatory follicle(s) >25mm **
- No CL**
- check twice 10d apart**
- lack of uterine tone/flaccid uterus
