We are strictly an AI/embryo operation. I went to school for both. Started with AI and developed such a passion for it continued on to embryo's.
The ability to choose from proven bulls is one benefit. No bull maintenance is another. Less risk of injury by not having a bull. However more labor and more times threw the chute for the cattle though. You have the ability with AI to close you calving window greatly which has MANY benefits.
I can pick each sire for each cow if I choose or a heifer bull for the heifer and a cow bull for the cows. Low birth rates or standard birth rates.
Heifer semen or bull semen.
If I want to add something or reduce something. Of course you never know what you'll get but if you want better udders you pick a bull that has proven to improve udders on most cows etc.
AI can be a wonderful tool. Especially for smaller facilities that can't make a bull cost effective.
A lot depends on how much going rates are for it or if you go to school and start doing it yourself. Over time it becomes much cheaper doing it yourself. IMO
Depending on how and who's doing your work can vary your conception rates greatly. If your just timed breeding after synchronization you'll get lower numbers. If your heat detecting and breeding that will greatly increase your conception rates. I think you said your talking about around 20 cows or so. Normally I'll get 18 out of 20 pregnant the 1st breeding. But that's here in my facilities with my heat detection etc. I've had many times where 20 out of 20 will get bred the 1st time around.
By culling those with poor breeding histories you also end up with much more fertile cattle. Fertile cattle means higher conception.
Some cows just won't breed via AI. They need that high dose of semen from a bull vs a 1/4cc straw. Here they grow wheels and head to the sale barn.
As far as buying bulls, the sale barn is a gamble. 1st a large portion of the time there's a reason an animal is there. The things the animals can pick up there are like rolling around a hospital floor
. You also have no idea of prior vaccination etc (most of the time). The animals are unproven (again most of the time) and that right there can be a huge gamble for you and your cattle.
QUARANTINE EVERYTHING AT LEAST 30 Days. Weather from a sale barn or a ranch. I've seen many herds contract something very bad from not quarantining animals. Bulls can have STD's that can cause all kinds of problems. If the origins and cattle a bulls been breeding (or bred while housed at the sale barn) are unknown have it tested. The last thing you want is an STD that causes all your cattle to abort. Another benefit of AI
Many years ago we bought a bull that threw 150-165 lb calves. We had more c-sections and pulls that year and lost most of the cows and calves from it. Even with immediately hauling to the vet when calving would start. Lesson learned. Very expensive lesson learned. That started my AI adventure
The ranches I deal with here that buy bulls or clean up bulls all buy from reputable ranches or from reputable ranches at bull sales. Most auction yards will have bull sales (and replacement heifer sales, bred cow sales etc) at least once a year. Maybe check one of those out?
I think I've rambled enough. Hope this helps a little
Just my opinions