Dairy 1

Question 1

definition of a transition cow?

Answer 1

3 weeks before calving until 3 weeks after calving

cow goes from dry cow, calving, to producing milk

Question 2

after calving, how long does the uterus take to involute?

Answer 2

21 days

Question 3

when do you do preg checks in DAIRY cows?

Answer 3

35 days, with ultrasound can see it earlier like day 28 to 30

Question 4

what is a “repeater cow”?

Answer 4

3+ unsuccessful AIs (cant get preggo) or shes been open for more than 90 days

Question 5

what are some characteristics of an ideal transition cow?

Answer 5

• 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

Question 6

what is special about the first cycle after giving birth?

Answer 6

the CL is short lived, only lasts 5 or 6 days compared to normal 17 days

Question 7

what is the “voluntary waiting period”?

Answer 7

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).

Question 8

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

Answer 8

PGF2 released, P4 decreases (CL gone), E2 increases, GnRH surge, LH surge, ovulation

Question 9

what are the 3 follicular development stages?

Answer 9

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.

Question 10

what is the role of P4 in follicular development?

Answer 10

high P4 suppresses LH pulses and maintains a dominant follicle at around 16-20mm

Question 11

please explain the graph (generally)

Answer 11

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

Question 12

LH is under the control of estradiol and progesterone. How?

Answer 12

estradiol inhibits LH and progesterone causes neg feedback to prevent GnRH (FSH and LH)

Question 13

following ovulation there is a rise in FSH–> WHY? explain the trends you see on this chart

Answer 13

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

Question 14

95% of cattle have how many waves?

Answer 14

2 or 3. heifers tend to have higher progesterone which means they have 3 waves usually

Question 15

describe the differences in a cow having a 2 wave cycle vs a 3 wave cycle

Answer 15

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

Question 16

describe what an ovarian cyst is (cystic ovarian disease)

Answer 16

when an anovulatory follicle that persists from day 6 to 10, is more than 20mm in diameter, and has no active luteal tissue

Question 17

that is the pathogenesis of an ovarian cyst?

Answer 17

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)

Question 18

what are some clinical signs of an ovarian cysts?

Answer 18

irregular estrus intervals, nymphomania, masculine aggressive behavior and sexual behavior–>estradiol is super high (being released by the big follicle)

Question 19

what is the recommended treatment for a follicular cysts vs an ovarian cysts?

Answer 19

follicular cysts: GnRH to induce an LH surge

luteal cysts: PGF2 to induce luteolysis

Question 20

what are the two types of ovarian management?

Answer 20

estrus synchronization, and ovulation synchronization

Question 21

why do we do ovarian management?

Answer 21

to reduce the time that a cow is not pregnanr after calving

Question 22

briefly, how does estrus synchronization work?

Answer 22

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)

Question 23

describe how ovulation synchronization works?

Answer 23

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.

Question 24

briefly describe what the following drugs are used for:
PGF2 (dinoprost)
GnRH (gonadorelin)
progesterone (CIDR/PRID)
E2 (banned)

Answer 24

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!!!

Question 25

what is the first step when doing an estrus synchronization protocol?

Answer 25

start with PGF2 to get rid of the CL and get rid of progesterone! In order for this to work the CL has to be the right age, can’t be too young or too old. Then give a second dose of PGF2 14 days later to kill any of the CLs that were too young to be affected b the first dose.

Question 26

if youre wanting to do an estrus synch program and you see on US that one of the cows doesn’t have a CL, should you still give it PGF2?

Answer 26

no! you can leave the ones without a CL and just give PGF2 to the ones with a CL, this is the “low hormone” approach

Question 27

what is one major problem you may encounter when doing an estrus synch program using PGF2 to remove the CLs?

Answer 27

estrus detection is quite long: 48 hours to up to 7 days after the second injection.

Question 28

true or false: detecting estrus is straight forward and relatively easy to do

Answer 28

false! it requires someone checking the cows multiple times a day for estrus behaviors which is very difficult to do. AND estrus is quite short so you could miss it!! They could show signs in the middle of the night and then you miss it

Question 29

what is the classic sign of estrus you look for when doing an estrus synch program? What is one problem with this?

Answer 29

standing heat/standing estrus, arching of the back. The problem is that many cows actually dont show this sign. The length of estrus is also decreasing (in regards to change over time in cow populations)

Question 30

what are some secondary ways to detect estrus?

Answer 30

mounting or following other cows, restlesness or increase in activity, not eating as much, rumnation decreases, red/swollen vulva, mucus discharge, reduction in milk production

Question 31

describe how the discharge looks in early vs late estrus

Answer 31

early: thick and sticky
late: liquidy–>inseminate 12 hours after this

Question 32

why, when using PGF2, is there so much variability when the cows actually go into estrus? after the second PGF2 injection it can take anywhere from 2 to 7 days to actually show estrus. WHY?

Answer 32

think of it this way:

if you give a cow PGF2 and the cow already has a dominant follicle ready to go, it will ovulate fairly quickly

BUT if you give PGF2 to a cow that doesn’t have a dominant follicle ready to (still has to recruit follicles and select dominant one), this process takes longer and therefore the animal wont show estrus signs for a few days still.