Brahmin are very weak animals that have been domesticated and herded throughout the years since the war. Brahmin can be seen wandering in herds around the Mojave Wasteland, but this is rare.
Through their domestication, they have been used primarily for meat and milk, and their hides are tanned to make leather. Traders use them to carry heavy loads, and some people keep them as pets.
As a result of the constant exposure to radiation, these formerly normal cows have sprouted a second independent head. Ironically, when brahmin are born with only one head, they are called mutated. Brahmin also have eight stomachs. According to Rose, male brahmin also have four testicles. Their skin has turned a toasty, dusty orange-red color from the fallout exposure and their horns have become a dirty brown. Their udder has also grown abnormally large (almost dragging on the ground).
Brahmin have a very minuscule amount of hit points and even a lower-leveled character can kill them with as much as a 10mm pistol. When brahmin attack, they utilize their horns and batter into a foe. This is not highly damaging but is still noticeable. When a brahmin is killed, it will let out a loud bellow and flop to the ground.
A regular brahmin with all the attributes mentioned above.
Malnourished brahmin are sickly brahmin that have been neglected and cannot find food on their own. Their meat is unaffected by their malnutrition. They can be found in various locations throughout the Mojave Wasteland, most notably Matthews Animal Husbandry Farm.
Malnourished brahmin calves are young brahmin that cannot find sufficient food to maintain full health, usually because they have been deserted by their owners. Their meat is unaffected by their malnutrition. They can be found across the Mojave at such places as the Matthews Animal Husbandry Farm. There is also one in front of Raul's shack.
Water brahmin serve a similar purpose to caravans in Fallout: New Vegas, although the only goods they carry are sacks of water, an essential for life in the Mojave Wasteland. These brahmin assist the Crimson Caravan in delivering water where it is required. Fixed locations are near Miguel's Pawn Shop and the 188 trading post. Although they have water packs, they won't have water when looted.
These are brahmin that are owned by the Fiends, and are located at Cook-Cook's fort. They are not part of the Fiend's faction cell, and are friendly to the player unless provoked. There are two unnamed "fiend brahmin" and one named "Queenie".
Queenie is Cook-Cook's favorite brahmin and if Queenie is killed, Cook-Cook will become frenzied, attacking anything in sight including his own gang.
If the player crouches, disarms their weapon, and presses the "Activate" button while in front of a brahmin, the brahmin will tip over (more specifically, enter a ragdoll state). This is known as brahmin tipping. Every time you push a brahmin (even if they are already on the ground), it counts toward the "Knocked Up" challenge.
Brahmin that are used by merchants to carry their wares are usually referred to as "pack brahmin". If they are carrying water, they are known as "water brahmin".
Brahmin with only one head are very rare (so much so that they never appear in game), and ironically are considered to be a mutation.
It is impossible to sever or destroy one brahmin head without the other.