26 Estrous Sync in the Bovine

How can estrous synch increase the short term profitability for a producer? (2)

- decreases cost of rebreeding

- increases reproductive efficiency

How can estrous synch increase the long term profitability for a producer? (2)

- change genetic makeup of the heard

- shift away from the "12 month" breeding season

What industry has started to use synchronization more?

dairy (production with AI)

What are the THREE reasons why the dairy industry has switched to synchronization and AI?

- eliminate the need for the bull on farm (cheaper)

- target superior milk production or component composition

- earlier pregnancy status

What are the TWO reason why synchronization is growing in the beef industry?

- uniform calf crop have enhanced marketability and market value

- live cover or Fixed time AI

T/F If you synchronize you induce cycylicaluty in some non cycling individuals

True

Why are some reasons why you would need synchronization?

embryo flush/transfer

What is probably the most important thing to consider if your producer wants to go down the path of synchronizing a heard?

owner compliance (this is bc they are going to be the ones giving the drugs and you need to know that they are one board so youre not wasting anyones time)

What are FOUR things that you need to consider for owner compliance?

- number of times through the chute

- times of day

- length of protocol

- record keeping

What is the avg cost per dose of prostaglandin (PG)?

$8

What is the avg cost per dose of GnRH?

$7

How much does it cost for a CIDR?

$21

What is the difference between a CIDR and MGA?

CIDR is an intravginal device that releases P4. MGA is P4 that is mixed into the feed and is only used in heifers

Why is MGA only used in heifers?

basically the people were lazy or broke or something like that and they did not want to pay/ have the time to go through the processing to get it approved in cows so its like very illegal

T/F You can use off label drugs for reproductive issues in cattle

False (did you not just read that paragraph, its illegal)

What are some things that you need to consider when deciding if there is going to be a live bull vs AI?

- number needed to be bred

- heat detection ( can be hard to capture)

What protocol minimize the times through the chute and most of the time the cattle are only AI once? What industry is this popular in?

7 day CO synch + CIDR, Beef

What protocol has the cattle going through thechute 2-3x per day and AI the cows 2-3X/day? What industry is this typically used in?

OVSynch, Dairy

What is the need to synchronize a heard?

all of the cows in a heard are randomly cycling and the whole point of synchronizing it to have all of the calves at once bc that is how the cattle industry makes profit

If you have a random herd of 100 cows, all averaging a 21 days cycle. How many cows will be in estrUS on any given day?

4-5 cows ( basically this is saying that if you bred all 100 of those cows only 4-5 of them would be at the right time to be bred)

T/F When synching cows, all of the cows will need every one of the drugs to be in the right timing to be bred

False, not every individual will need every drug

Why do we gaf if the herd in synch or not?

errors in synchronization happen

What is the goal of synchronizing a herd?

by the cumulative effort of combo drugs to all of the females at the various stages all of the stages get manipulated to ovulate near the time of breeding (in very basic terms you want all of the to have the LH surge at the same time so that they can all ovulate at the same time)

What are the THREE things that need to happen for ovulation to happen?

1. Dominant follcile

2. LH surge

3. No Progesterone

What are the FOUR broad protocols that can be used to synch?

- 1 shot PG

- 2 shot PG

- Ovsynch 56

- 7 day Synch with CIDR

What is the whole reason that we use PGF2a?

to lyse the CL

If you give a shot of PG, how long is it until the cow comes back into heat?

5-7 days

What structure will not respond to the PG when given?

CH

When in the cycle does the CH form?

metestrus ( day 5-6)

What hormone does the CL produce?

progesterone

T/F Lyse CL= Low P4= allows for estrus

True

Describe the 1 shot PG synch protocol

give once shot in the middle of the cycle (because that is when a mature CL is present and will respond), at that time about 2/3 of the cows will have a CL that will lyse and they will come into heat 3-5 days later

Describe the 2 shot PG protocol

The first shot will bring 2/3 of the cows into heat at the same time (they ovulate and a new CL forms at the same time). The second shot comes along 11-14 days later to get the rest of to catch up and lyse all of the CL at the same time

T/F The 1/3 that did not come into heat with the first shot couldve had a CH so that's why you have to wait 11-14 days for the follicular waves to grow another follicle

True

You go out to a farm of COWS and the producer wants you to synch them using the 2 shot PG methond. What do you do?

Give the first shot that day and come day 14 days later and give the 2nd shot of PG, then timed AI will happen 72-80 hours later

You go out to a farm of HEIFERS and the producer wants you to synch them using the 2 shot PG methond. What do you do?

Give the first shot that day and come 11 days later and give the 2nd shot of PG, then timed AI will happen 60-68 hours later

You have a massive dairy producer, DOUG DIMMADONE, that wants you to synch his herd using the OvSynch56. How do you achieve this?

- On day 1, you give a shot of GnRH (this will induce the follicles to grow and produce a dominant follicle)

- 7 days later, you give PGF (this lyses the CL)

- 56 hours later, you give a shot of GnRH (this will induce the LH surge and cause ovulation)

- 16 hours later, you AI the herd

What does endogenous GnRH do?

stimulates FSH and LH

What does exogenous GnRH do?

stimulates LH

If you give a shot of GnRH when there is LOW P4, what would you expect to happen?

ovulation

If you give a shot of GnRH when there is HIGH P4, what would you expect to happen?

follicular turn over

Going back to Dougie. Would you expect when you give the 2nd shot of GnRH to be in a state of high or low P4?

low (this is bc the CL was lysed and you are hoping for ovulation)

Finish the equation:

Low P4 + GnRH= _____ -> =

Low P4 + GnRH= LH -> = ovulation

What does synchronizing help to "ensure"?

helps to narrow the window of ovulation

super fun example time

god no please (IK)

You have your gold star cow that is going to ovulate on her own, Snap. Her sisters are not as lucky, Crackle and Pop. Crackle does not have a dominant follicle on her ovary but she just need to have once more waves. Wha do you do for Crackle to ovulate with her sister?

you give her a shot of PGF2a and that causes the CL to lyse. This is followed by a shot of GnRH to stimulate follicular growth and LH surge to make sure that she ovulated on time

Now good ole Pop. She has TINY follicles, 8mm to be specific. What does this mean?

The follicles will not respond to LH or GnRH

Well daggumit, what do you need to do for POP?

she will get a shot of GnRH which results in follicular turnover (this is bc there is high P4 present). Then once the follicle is big enough to respond, you give a shot of PGF2a, this causes the CL to lyse (P4 lowers). Then give another shot of GnRH which will lead to ovulation

With the OvSynch56 when you are giving the first shot of GnRH, is this is a stage of high or low P4?

tbh we dont know

If there is a high state of P4 with that first shot, what will happen?

if P4 is high, there is a CL present. This will lead to follicular turnover and then the PGF2a will come in 7 days later and lyse it

If there is a low state of P4 with that first shot, what will happen?

there is no CL present so it will cause there to be ovulation and this leads to a CH forming and the CL will develop 7 days later and be lysed by the PGF2a

Why must you wait 7 days to give the shot of PGF2a?

you need to allow enough time if a CH was made to be able to respond to the shot of PG

What happens if after the first shot of GnRH the cow goes through a natural luteolysis?

you go ahead and shove that CIDR up in there to act like there is a fake CL there (the CIDR has P4 so it acts as a CL)

T/F The CIDR prolongs the time until the cow has a LH surge

True

What is the 7 days CO-Synch + CIDR protocol?

- on day 0 you give a shot of GnRH ( this will promote follicular turnover)

- day 0- day 7- the cows have a CIDR in ( this stimulates that a CL is there)

- On day 7, a shot of PG is given (to lyse the CL)

- 60-66 hours later, GnRH and AI is done

T/F On day 7, when you remove the exogenous and/or endogenous source of P4 they all should come into heat at the same time

True

What does the first shot of GnRH do?

removes the influential follicles to start a new wave

What are the TWO big differences between 7 day CO- Synch + CIDR and OvSynch?

CIDR, number of times they go through the chute

Why do you have to wait the 60-66 hours after the shot of PG is given to AI?

to ensure that the drug is absorbed and the CL is lysed and ovulation has occured 30 hrs later

What is the point of superovulation?

to increase the number of offspring by valuable female

What is it called when you superovulate, breed and the flush embryos from donor a 1 week gestation?

Multiple Ovulation Embryo Transfer (MOET)

What is it called wehn there is an increased number of follicles then you aspirate the oocyte then do IVF?

SUperstimulation/ Ovum Pickup

T/F In the MOET synchronization, you need the donor and recipiant to match up

True

When should you put the embryo in the freezer?

the same day it was flushed out

What protocol is the recipient of MOET on?

standard (heat detection)

What drug if present shows you that the producer wanted to super ovulate the cow?

FSH

What is the exogenous form of FSH?

Follitropin V

T/F You use FSH to rescue follicles that would normally be selected against so that more can become dominant

True