You can extract blood in a tek sleeping pod. It works pretty well since you don’t have to eat from the healing. It’s end game af but if you got it and you want a bat or blood stalker you can have hundreds of blood packs in minutes.
Tame a low lvl desmodus before you find a high level farm up minimally 40 bloodpacks and then farm more after the low lvl tame to get a high level and let it suck blood from tamed dinos i prefer dire wolfs or daedons so the taming effectiveness goes up and you dont lose a lot of lvls
Try to tame a low level one first so you can farm blood packs with it, it'll shorten the farming time for a high level bat.
You can also tame a Daeodon first and use it's healing aura when extracting the first few packs, the pig can also help you raise the taming effectiveness for future high level tames, just let it wander on passive near the Desmodus you want to tame, keep some blood packs on it's inventory and let it get picked, it'll raise the effectiveness.
Let it pick you afterwards and feed on your blood packs to raise the taming meter, when it's about to tame, be sure to check if the effectiveness is close to 100%, if not just let it pick the Daeodon some more.