Use of GnRH in synch protocols

[townfarmer]

I'm planning to have my first attempt at AI in a couple of months. I've ordered all the equipment. I'm currently working out my order for synch medications for a group of five heifers. I've looked at a variety of different protocols. Are many people on this site using GnRH in their synch protocols?

Andrew

 

[dun]

GnRH restarts the cycle clock, why wouldn;t you use it?

 

[wbvs58]

Andrew we have access to Ciderol (Oestrogen) here. I would use it in preference to GnRH. Much more basic and works very well and very economical. You can still use the GnRH at time of insemination if you wish. Get in touch and I can give you some of the protocols.
Ken

 

[Stocker Steve]

You can still use the GnRH at time of insemination if you wish. Ken

How much benefit do you see from this?

 

[dun]

You can still use the GnRH at time of insemination if you wish. Ken

How much benefit do you see from this?

This year we did 2 with GnRH, one settled one didn;t

 

[Alan]

You can still use the GnRH at time of insemination if you wish. Ken

How much benefit do you see from this?

I use GnRH twice in the synch? GnRH and insert CIDR's, 7 days later, lute and pull CIDR's. I think it's 66 hours later + or - 6 hrs AI and another GnRH (I'm not looking at my book, so double check the time table before you take my technique as gospel). I get about 60 to 70 percent bred, so I keep a decent clean up bull most of the time. I haven't AI for two years now, I'm moving my calving season to an early calving date, but that's a different story, should be good to AI next year.

 

[NWMoAngus]

I have been using AI since the mid 80s. Used to use MGA medicated feed followed by a Lute, Bovalene or Estrumate shot. Usually got about half the heifers bred AI. For the past four years or so we have been following the Gnrh & Cidr protocol on both heifers and cows. We insert the Cidr and give a shot of 2 cc of Factril on day one. On day 7 or 8 we pull the Cidr and give them a shot of Estrumate. The heifers are bred after observing standing heat or at about 65 hours after the Estrumate shot. The cows are bred after observed standing heat or at 72 hours after the Estrumate shot. We get about 75% of the heifers and 65% or so of the cows bred AI using this protocol. It is expensive and time consuming. But it beats getting up early and going out late to watch cows for heat.

 

[townfarmer]

Andrew we have access to Ciderol (Oestrogen) here. I would use it in preference to GnRH. Much more basic and works very well and very economical. You can still use the GnRH at time of insemination if you wish. Get in touch and I can give you some of the protocols.
Ken

I should have been clearer in my original post. I was meaning using GnRH at time of insemination as you mentioned. I'd be interested in hearing your protocol Ken.

The protocol I intended to follow was:

Day 0 - insert cidrs, inject ciderol

Day 8 - pull cidrs and inject prostaglandin

Day 9 - inject ciderol

Day 10 - inseminate

I have heard a few anecdotes recently about people improving their conception rates by injecting GnRH at the time of AI.

GnRH restarts the cycle clock, why wouldn;t you use it?

My understanding is the rationale for injecting at insemination was for enhancing the growth of ovarian follicles.

Andrew

Andrew

 

[dun]

My understanding is the rationale for injecting at insemination was for enhancing the growth of ovarian follicles.

Andrew

Andrew

At AI time it doesn;t make the follicle grow any more. It makes her ovulate, i.e. it makes the follicle rupture and release the egg. If given before there is a viable egg it just causes her to ovulate and start the heat cycle over from the beginning

 

[townfarmer]

My understanding is the rationale for injecting at insemination was for enhancing the growth of ovarian follicles.

Andrew

Andrew

At AI time it doesn;t make the follicle grow any more. It makes her ovulate, i.e. it makes the follicle rupture and release the egg. If given before there is a viable egg it just causes her to ovulate and start the heat cycle over from the beginning

Thanks Dun, that makes sense.

Andrew

 

[wbvs58]

Yes that's basically the protocol Andrew for fixed time inseminations the inseminations being between 48 and 54 hrs after the PG. I find that 48 hrs is fine for heifers but I would suggest stretching it out to the 54 hrs for the mature cows and I think the GnRH could be usefull though I don't use it. The Ciderol gives the ovaries a bit of a tickle up and it is very reliable at least 90% of cows will be in standing heat in a very narrow window.
This year I will be going back to some heat detection with the mature cows. Any on heat at 48 hrs will be inseminated which should be about 50%, the rest of them get the Ciderol and are inseminated 24 hrs later. I will still do the heifers the fixed time as I had very good results with it last year.
I realise that you are looking at the logistics of getting it done in a short period of time over a weekend and probably the fixed time would better suit but try and plan the inseminations for mature cows later in the window.
Another suggestion is don't overload your work by synchronising too many at once until you get to know your capabilities as well as getting things organised. With my problems with my hands and arms I just synchronise 4 or 5 at a time and the heat detection protocol will usually cut the number to inseminate at one time by half. If I have to do more than 5 at one time my arms are too fatigued and are just like jelly and useless.
Ken