The Screams of Brahmin (holotape)

 is a paper note in Fallout: New Vegas. It can be found on a Nightkin you have to kill near the McBride House.

Transcript
The courier finds a holotape on the body of the nightkin, but it turns into a note in the courier's inventory.

The hatred towards the brahmin is caused by severe psychotic side effects of prolonged Stealth Boy use.