Yes, GnRH doesnt force a cow into estrus, or estrous for that matter. Each hormone in the cow acts like a trigger to another hormone. GnRH for instance only triggers the release of FSH. FSH (Follicle Stimulating Hormone) is what stimulates new follicles to produce oocytes. But I must say, GnRH really has nothing to do with the formation of a corpus luteum. A CL is only formed AFTER estrous (heat/standing heat) and ovulation. Then its Progesterone that maintains it.
I am curious though... Did you simply give PG or to be technical PGf2alpha, then heat detect?
Or did you give GnRH, wait 7 Days then PG, then heat detect?
If you gave the GnRH, and you may know this, but it is important to start heat detection 2 days before the PG shot on the 7th day. This is because it is very common to have 5-20% of cattle come into heat without the PG shot, on the 5th day.
I do have to agree that on first calf heifers I would give them a little more time to recover before attempting to re-breed, and they usually are a little tougher to get bred with AI.
However, that doesnt mean not to try. I strongly encourage you to keep trying. There will always be some growing pains when you first start trying to AI cattle. Most people go to these schools, go home, hit a rough spot kinda like you have, then give up. Persistence will absolutely pay off! With every year that passes you will get better and have much better efficiency.
And you mentioned CIDR's.... I would strongly recommend them. Although costly, they are well worth it. PG only works on cows that are in a certain part of their cycle, (I wont be too technical here unless you'd like me to explain) and therefore you will most likely always have a few not come into heat. CIDR's simply "arrest" all of these cattle at the proper of their cycle so they are able to respond to PG. So theoretically you should have 100% heat. Of course we dont live in a perfect world and it doesnt always happen that way. But the do increase the results.
And I have to disagree with the night heat detection. Yes, often cattle do come into heat at night. Seen it hundreds of times.. But you said you were using patches. Therefore you have no need to check them then. Thats why you bought the patches! But if that would make you feel like you did all you could, then go for it! Personally, I feel like its a waste of time.
Once again, keep trying! You'll get it all going your way soon enough!
PS.. I didnt mean to offend anyone with opposing opinions. I was only stating mine from my own experience and education. I would like to hear opposing opinions on the matter though. Thats how Ive learned what I have. By taking others opinions and trying them and finding what works best for me. Thanks!
If it aint Angus, It's just BULL!
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