Blood is the substance that carries nutrients to hair cells.
It is also useful for feeding mosquitoes, which make great pets.
Mosquitoes are easy to care for and require no training. They are barkless, faithful, and able to keep up with you on the trail.
And they self-replicate in the millions.
You could even go into business selling them online.
There's your idea.
Now run with it.
(Other critters available by special request.)