Dairy 1 Flashcards
definition of a transition cow?
3 weeks before calving until 3 weeks after calving
cow goes from dry cow, calving, to producing milk
after calving, how long does the uterus take to involute?
21 days
when do you do preg checks in DAIRY cows?
35 days, with ultrasound can see it earlier like day 28 to 30
what is a “repeater cow”?
3+ unsuccessful AIs (cant get preggo) or shes been open for more than 90 days
what are some characteristics of an ideal transition cow?
- calving without complications
- free of metabolic or infectious disease
- recovers feed intake (idk what this means)
- rapid increase in milk production
- rapid return to reproductivity cycle
what is special about the first cycle after giving birth?
the CL is short lived, only lasts 5 or 6 days compared to normal 17 days
what is the “voluntary waiting period”?
the interval during post partum when producers choose not to breed–>they do this because the 1st ovulation is often silent with a short CL lifespan, and the 2nd ovulation usually has a low quality oocyte.
he said in class that in order for the animal to show estrus behaviors and ovulate, there needs to be a priming with progesterone, aka, we need a CL and we need it to produce progesterone! So if you palpate an animal dat day 30 after she’s given birth and you can feel a CL, it means she’s cycling and her body is doing a few “mini” cycles in order to create a CL (which will produce progesterone and prime the hypothalamus).
theres a friggin slide with all the hormones and what they doin leading up to ovulation in the diary cow. try to remember it or simply remind yourself
PGF2 released, P4 decreases (CL gone), E2 increases, GnRH surge, LH surge, ovulation
what are the 3 follicular development stages?
recruitment/emergence: a group of antral (small) follicles less than 4mm grow under the influence of FSH. This takes about 2-3 days for them to grow.
selection/deviation: once the follicles have grown a bit, this creates a follicular wave, and a number of these follicles are selected (based on the species of animal). These follicles grow until they get about 9mm in size. At this point FSH is decreasing because there are many follicles growing at once time and so inhibin and estradiol starts to get high creating negative feedback. The follicles that are not able to grow without FSH will undergo atresia, and 1 or 2 follicles change their dependency from FSH to LH.
Dominance: Usually at this point 1 follicle is able to continue growing in response to LH. This follicle will cause an increase in estradiol to create the preovulatory signal. This dominant follicle is around 16mm.
what is the role of P4 in follicular development?
high P4 suppresses LH pulses and maintains a dominant follicle at around 16-20mm
please explain the graph (generally)
according to the prof:
FSH from hypothalamus causes follicles to develop. Follicles produce estrogen which increases, and this estrogen has a positive feedback mechanism on the hypothalamus to send more LH. This makes sense, because
as you get closer to ovulation, LH surges increase in frequency until it causes a massive spike. This causes ovulation
LH is under the control of estradiol and progesterone. How?
estradiol inhibits LH and progesterone causes neg feedback to prevent GnRH (FSH and LH)
following ovulation there is a rise in FSH–> WHY? explain the trends you see on this chart
the follicle was producing estradiol and inhibin and when it ovulates all of that suddenly decreases. So as soon as estradiol and inhibin are gone, FSH can come back. As a result of this FSH now coming back, a group of follicles can be recruited. If there is enough LH, a follicle will be selected, but it will not ovulate. WHY? because there is progesterone from the CL from our most recent ovulation and progesterone will inhibit that LH surge we need in order for ovulation to happen. Since this follicle doesn’t ovulate, it undergoes atresia. Now we get FSH increasing again because estradiol and inhibin are gone! Same thing happens as before; recruitment and selection of a dominant follicle! This time though, we have PGF2 being secreted which causes the CL to die and now our progesterone is gone–>now the follicle can ovulate! because the hypothalamus has no neg feedback and can release GnRH
95% of cattle have how many waves?
2 or 3. heifers tend to have higher progesterone which means they have 3 waves usually
describe the differences in a cow having a 2 wave cycle vs a 3 wave cycle
2 waves: lower progesterone, so LH ins’t inhibited as much. luteolysis happens at day 16
3 waves: the follicles regress sooner because there’s more progesterone which blocks LH. luteolysis happens at day 19
describe what an ovarian cyst is (cystic ovarian disease)
when an anovulatory follicle that persists from day 6 to 10, is more than 20mm in diameter, and has no active luteal tissue
that is the pathogenesis of an ovarian cyst?
high yield cows in a negative energy balance which means not enough P4 or E2, this means the LH receptors are down regulated, leading to a follicle which has decreases sensitivity to LH, which means the follicle doesn’t ovulate. This leads to a dominant follicle that persists and follicular waves stop creating anestrus. (big follicle making E2 and inhibin=no FSH to stimulate a new wave)
what are some clinical signs of an ovarian cysts?
irregular estrus intervals, nymphomania, masculine aggressive behavior and sexual behavior–>estradiol is super high (being released by the big follicle)
what is the recommended treatment for a follicular cysts vs an ovarian cysts?
follicular cysts: GnRH to induce an LH surge
luteal cysts: PGF2 to induce luteolysis
what are the two types of ovarian management?
estrus synchronization, and ovulation synchronization
why do we do ovarian management?
to reduce the time that a cow is not pregnanr after calving
briefly, how does estrus synchronization work?
focus on the cow’s behavior and use an AI protocol based on observed estrus. For example: if you see estrus behavior in the AM, you inseminate in the PM and visa versa (insemiante 12 hours after you observe the behavior)
describe how ovulation synchronization works?
we control follicular growth and the induction of ovulation and we don’t care about the behavior. AI is at a fixed time and is not based on observed behavior.
briefly describe what the following drugs are used for:
PGF2 (dinoprost)
GnRH (gonadorelin)
progesterone (CIDR/PRID)
E2 (banned)
PGF2 (dinoprost): kills the CL/luteolysis
GnRH (Gonadorelin): induces follicular growth/ovulation
progesterone: maintain pregnancy or use in animals that are not cycling
E2: same as GnRH but banned!!!
