Just to clarify this for some other readers:
An 'American barn' style consists of rows of loose boxes facing each other covered by a central roof separated by an alleyway.
Stalls, or standing stalls, are rectangular stalls big enough for a horse to stand in comfortably but not big enough to roll or walk around in. Horses have to be tied constantly.
Loose boxes in shed rows are the most common in the UK and consist of three or four rows that face each other and open up into a central courtyard, which is not covered.
Onto the pros and cons now.
American Barn Pros:
- Horses are able to see each other from the aisle and sometimes between stall walls, which makes them more comfortable as they can see other horses.
- They are able to move about and have the freedom to roll, lie down, and have separate eating and defecating areas.
- Since stalls are covered, horses stay warmer in winter and cleaner year-round.
- Stalls can easily be converted into double stalls for breeding or recuperation.
American Barn Cons:
- Lack of air circulation. Horses have very sensitive respiratory systems and the enclosed space may attribute to breathing problems.
- Horses often become bored in their stalls when not able to see the outside world, often contributing to stress-caused vices including weaving, stall-kicking, cribbing, wood chewing, windsucking, blanket ripping, biting, head tossing, self-mulitation, and becomming cast (not a vice but a bad habit).
Standing Stalls Pros:
- Little chance of becomming cast in the enclosed space.
- Small size of stalls is cheaper to build and maintain.
Standing Stalls Cons:
- When being tied, many horses are reluctant to lie down. This can lead to fatigue.
- Lack of movement may result in fluids pooling in the legs, causing many foot-related problems.
- Lack of movement may mean horse has to stand in wet bedding for long periods of time, which is a breeding ground for thrush, abscesses, and other foot problems.
Loose boxes Pros:
- Horses can follow their biological clock better as they can see the sun, weather, etc.
- Fresh air promotes healthy respriatory system.
- Horses can see eachother, leading to reduced stress than in a tie-stall situation.
Loose boxes Cons:
- Close confinement to other horses may lead to conflict and fighting.
- Driving rain or snow increases chance of horses catching a chill or sickness.
- Airborne diseases are quickly spread in the wind if one horse is sick.
Hope that helps. Good luck with your assignment :)