Timed Synched AI Steps... Why?

[Alan]

I could probably research this and get my answer, but 3/4 of the education is in the discussion.

I'm getting ready to AI my cattle, here is the timed synch system I'm using, I'm curious to know what each step does.

Day 0: 2cc GnRh IM, insert CIDR (what does the shot of Fertagyl do, and the function of the CIDR?)

Day 7: 5cc PG IM, remove CIDR (what does the Lutalyse do at this step?)

54hrs +/- 2hrs: (Standing heat) AI plus 2cc GnRH IM (Okay, I have a pretty good idea what the semen does, but what is the purpose of the second shot of Fertagyl?)

Thanks,
Alan

 

[milkmaid]

Day 0: 2cc GnRh IM, insert CIDR (what does the shot of Fertagyl do, and the function of the CIDR?)

GnRH causes the pituitary gland to release LH (lutenizing hormone) and FSH (follicle stimulating hormone). The CIDR releases progesterone, the main hormone released when the cow is not in estrus (or pregnant). So the CIDR is to cause her body to think she's in that inbetween stage, and the GnRH causes a CL to mature...

Day 7: 5cc PG IM, remove CIDR (what does the Lutalyse do at this step?)

...Lute at this point will destroy the CL you've created, causing the cow to come into heat...

54hrs +/- 2hrs: (Standing heat) AI plus 2cc GnRH IM (Okay, I have a pretty good idea what the semen does, but what is the purpose of the second shot of Fertagyl?)

...and the 2nd shot of GnRH stimulates the ovary to create a strong CL, necessary for maintanence of pregnancy.

Least that's the way I understand it.

 

[Alan]

Thanks, MM a very complete clear answer.

Alan

 

[bandit80]

Day 0: 2cc GnRh IM, insert CIDR (what does the shot of Fertagyl do, and the function of the CIDR?)

GnRH causes the pituitary gland to release LH (lutenizing hormone) and FSH (follicle stimulating hormone). The CIDR releases progesterone, the main hormone released when the cow is not in estrus (or pregnant). So the CIDR is to cause her body to think she's in that inbetween stage, and the GnRH causes a CL to mature...

Day 7: 5cc PG IM, remove CIDR (what does the Lutalyse do at this step?)

...Lute at this point will destroy the CL you've created, causing the cow to come into heat...

54hrs +/- 2hrs: (Standing heat) AI plus 2cc GnRH IM (Okay, I have a pretty good idea what the semen does, but what is the purpose of the second shot of Fertagyl?)

...and the 2nd shot of GnRH stimulates the ovary to create a strong CL, necessary for maintanence of pregnancy.

Least that's the way I understand it.

Been a few years since Bovine Reproductive Technology, but I think you might be wrong. I may be wrong to, so I hope someone clarifies.

I agree with your points except the role of GnRH. I believe the GnRH causes ovulation of the follicle, not to create a strong CL. The first GnRH is to essentially get all of the females on the same page. Thus, all will have just ovulated a follice and start a new follicular wave. (Assuming all cows are cylcing) The CIDR does release progesterone, causing the cow to believe she is starting her cycle over again. (It has also been shown to initiate estrous, but that is getting too complex.) The presence of the CIDR causes a CL (Corpus Luteum) to form. The lutalyse will cause the CL to break down, and the GnRH will stimulate the ovulation of a follicle that is capable of conceiving. The first GnRH will insure that there are not any "aged" follicles that are trying to join with a sperm. Aged follicles have a horrible conception rate.

Again, I may be wrong, but that is what I recall without getting my book out.

 

[KNERSIE]

Day 0: 2cc GnRh IM, insert CIDR (what does the shot of Fertagyl do, and the function of the CIDR?)

GnRH causes the pituitary gland to release LH (lutenizing hormone) and FSH (follicle stimulating hormone). The CIDR releases progesterone, the main hormone released when the cow is not in estrus (or pregnant). So the CIDR is to cause her body to think she's in that inbetween stage, and the GnRH causes a CL to mature...

Day 7: 5cc PG IM, remove CIDR (what does the Lutalyse do at this step?)

...Lute at this point will destroy the CL you've created, causing the cow to come into heat...

54hrs +/- 2hrs: (Standing heat) AI plus 2cc GnRH IM (Okay, I have a pretty good idea what the semen does, but what is the purpose of the second shot of Fertagyl?)

...and the 2nd shot of GnRH stimulates the ovary to create a strong CL, necessary for maintanence of pregnancy.

Least that's the way I understand it.

Been a few years since Bovine Reproductive Technology, but I think you might be wrong. I may be wrong to, so I hope someone clarifies.

I agree with your points except the role of GnRH. I believe the GnRH causes ovulation of the follicle, not to create a strong CL. The first GnRH is to essentially get all of the females on the same page. Thus, all will have just ovulated a follice and start a new follicular wave. (Assuming all cows are cylcing) The CIDR does release progesterone, causing the cow to believe she is starting her cycle over again. (It has also been shown to initiate estrous, but that is getting too complex.) The presence of the CIDR causes a CL (Corpus Luteum) to form. The lutalyse will cause the CL to break down, and the GnRH will stimulate the ovulation of a follicle that is capable of conceiving. The first GnRH will insure that there are not any "aged" follicles that are trying to join with a sperm. Aged follicles have a horrible conception rate.

Again, I may be wrong, but that is what I recall without getting my book out.

Your memory is spot on.

 

[milkmaid]

Bandit -- I'm going to disagree with you on that one. GnRH does start a new follicular wave as it releases FSH which stimulates follicle growth, but it also initiates development of a CL. I looked it up the other day to answer someone else's question. Copied and pasted...

• GnRH: Gonadotropin-releasing hormone. A hormone made by the hypothalamus (part of the brain). GnRH causes the pituitary gland to make luteinizing hormone (LH) and follicle-stimulating hormone (FSH). These hormones are involved in reproduction. Also called gonadotropin-releasing hormone.
  
  GnRH is the abbreviation for gonadotropin releasing hormone, a natural hormone that is released from the hypothalamus in the brain. GnRH causes the release of two other hormones known as gonadotropins from the pituitary gland. Luteinizing hormone (LH) and follicle stimulating hormone (FSH) are the gonadotropins. During the normal estrous cycle, when the proper signals are sent to the hypothalamus, GnRH is released to cause the release of these gonadotropins, which have an impact on the ovary. One of these effects is the release of a high level of LH, termed an LH surge, which causes ovulation of a follicle. This LH surge also initiates development of a new corpus luteum (CL) on the ovary.

 

[bandit80]

GnRH is released to cause the release of these gonadotropins, which have an impact on the ovary. One of these effects is the release of a high level of LH, termed an LH surge, which causes ovulation of a follicle. This LH surge also initiates development of a new corpus luteum (CL) on the ovary.[/list]

So I guess maybe we are both right. GnRH causes the release of FSH and LH. LH in turn stimulates the ovary to ovulate the follicle, and then form a CL.

I"m pickin' up what you are puttin' down.

 

[dun]

GnRH is released to cause the release of these gonadotropins, which have an impact on the ovary. One of these effects is the release of a high level of LH, termed an LH surge, which causes ovulation of a follicle. This LH surge also initiates development of a new corpus luteum (CL) on the ovary.[/list]

So I guess maybe we are both right. GnRH causes the release of FSH and LH. LH in turn stimulates the ovary to ovulate the follicle, and then form a CL.

I"m pickin' up what you are puttin' down.

The whole point of the GnRH is to start a new follicular wave. That way all of the cows given a shot on the same day are all in the same state.

 

[Red Bull Breeder]

The second shot of GnRH is to cause ovulation, according to ABS guy.

 

[JHH]

OK, I also just got done A-Iing cows and done the same as Alan. My question is WHY do we keep the bull out for 14 days if they started a new cycle? Wouldnt they come in 18 days give or take a few? I am not saying to keep your bull in while A-Ing but couldnt you put him back in 5 days later? And still be relativly sure that you had an A-I calf and not the bulls calf?

My bull is still in lot but I was thinking of putting him back in 7- 10 days.Just a dumb question.

 

[KNERSIE]

OK, I also just got done A-Iing cows and done the same as Alan. My question is WHY do we keep the bull out for 14 days if they started a new cycle? Wouldnt they come in 18 days give or take a few? I am not saying to keep your bull in while A-Ing but couldnt you put him back in 5 days later? And still be relativly sure that you had an A-I calf and not the bulls calf?

My bull is still in lot but I was thinking of putting him back in 7- 10 days.Just a dumb question.

If you are sure all your cows reacted on the synchronisation, you might as well put the bull in as soon as everyone is out of standing heat. The reason for keeping the bull out is if one didn't cycle when expected and had a natural heat somewhere inbetween the AI date and the next expected heat 18-22 days later you'll never know whether its an AI calf or not. Unless you DNA test off course

 

[S&S Farms]

OK, I also just got done A-Iing cows and done the same as Alan. My question is WHY do we keep the bull out for 14 days if they started a new cycle? Wouldnt they come in 18 days give or take a few? I am not saying to keep your bull in while A-Ing but couldnt you put him back in 5 days later? And still be relativly sure that you had an A-I calf and not the bulls calf?

My bull is still in lot but I was thinking of putting him back in 7- 10 days.Just a dumb question.

Cows do not all have the same gestation length. We plan on a 14 day window around the calculated AI date. If you are using different breeds of bulls from your clean up bull put them right in we do with our commercial herd AI to angus, herefords clean up.

Jeff

 

[Double R Ranch]

My semen provider says that you pull CIDR on day 7 and give Lute. Unless coming into heat prior to the 72 hour mark from when you pulled cidr you breed at 72 hours and give GNRH. Plus when you pull CIDR take calves off of cows for 48 hours to up conception. Claims that the cow puts its nutrience into the repro track.
The reason I am throwing this out there is lately our SYNC take rate hasn't been very good. About half of each group bred is taking. The other comes back into heat in 18-21 days. Now we don't have a "clean up bull" so I am getting those who come into heat again on the second breeding. (natural heat). They take every time on the second go round. I am starting to question this 72 hour mark a bit. It is getting pretty frustrating. My confidence is getting a bit shattered I guess. A year out of school and figured I would have a better first time bred count by now. Do get first times when spot a standing heat and breed without the sync. See standing heat and breed 10 hours later. They are taking every time.
What do you all think?
Double R

 

[dun]

Frequently induced heats, even if a standing heat is observed from it, are not as fertile as a natural heat.

 

[novatech]

I have used induced heats just to retime them so they don,t come into standing on Sunday. Sometimes it seems like they know when I have other plans.