Timing AI during a natural heat cycle

[branguscowgirl]

I AI my Brangus on their natural heat cycles. As some of you know, it can be challenging. I observe for mounting activity at least 30 min. every morning and evening. But that is the minimum, usually more frequent. I know when they are cycling, (I have calendared 18-24 days from their last heat.)
Once they are in standing heat, (not walking away with other cows mounting) I will count forward and breed at 14 hrs.. However, my Brangus tend to have really long heat cycles. Many times they are still standing to be mounted 24-36 hours from the start time. So I breed them again 2-3 more times. (I have plenty of semen from bulls I previously collected. So cost is minimal.)
My vet can't believe how long my cows stand. (Cervix wide open.)

My question is, what are the stand and breed times on everyone elses cattle??

 

[dun]

I subscribe to the am pm rule. If one is still in heat at the next check I breed and give a shot of GnRH

 

[Putangitangi]

If I see the start of standing and the cow/heifer is standing for several hours, I'll inseminate from 10 - 18 hours after the start. If I don't see the start and can't get a reasonable estimate (because of time last observed) or if the standing heat is really short, I'll inseminate within six hours of the end. Sometimes I follow cows around for some time, trying to figure out if they've stopped standing or not.

I like the cows whose timing will fit into either regime; then I feel sure I'm going to get them and I like it even better if that time is in the morning or evening, not the middle of the night or in the hottest part of the day.

Somewhere I got half-way through collating all my inseminations to see which ones had been successful on what timings. It's a job for a long winter's day.

 

[branguscowgirl]

Thanks for the replies. I have never used the GnRH. It might be something for me to try.

 

[redcowsrule33]

I used to do am/pm, switched to once a day (either standing the night before or the morning of breeding) and have seen no changes in conception rates.