The articles below will help you and explains that a lack of methionine (which is not present in polyvisol but is in aviacharge 2000 which can be purchased at McMurry or Strombergs) or if you go to a petstore and look in the bird section at the vitamins they have there many specially formulated for birds in molt will have methionine....
http://www.vetcareindia.com/p_bul_cannibalism.htm
(a very small excerpt from this excellent article)
..."Slow feathering birds are most prone to cannibalism: Take extra precautions with slow feathering birds. Most cannibalism occurs during feather growth in young fowl. Birds with slow feathering have immature tender feathers exposed for longer periods of time leaving them open to damage from pecking. Don't raise slow feathering birds with other fowl.
Managemental Causes
Overcrowding: Crowding the house with more birds than its capacity can lead to cannibalism
Excessive heat: When the birds become uncomfortably hot they can become extremely cannibalistic.
Excessive light: Extremely bright light or excessively long periods of light will cause birds to become hostile towards one another. Constant light can be stressful to the birds.
Absence of feed or water or a shortage of feeder and waterer space: If the birds have to fight for food and water, or if the birds are always hungry they will increase pecking.
Mixing of different types and colors of fowl: Mixing different ages of fowl or fowl with different traits promotes pecking by disrupting the flock's normal pecking order. Curiosity can also start pecking.
Abrupt changes in environment or management practices: If you plan to move young birds to a new location, it is best to move some of their feeders and waterers with them in order to help them adapt. When you change over to larger feeders and waterers it is helpful to leave the smaller equipment in the pen for a few days to help during the change.
Brightly lit nests or shortage of nesting boxes: Vent pecking by layers is also a common problem.
During egg laying the cloaca may become damaged and distended especially with the passage of large eggs and this protrusion of the vent may be an attractant to other birds due to its stark color difference against the white body.
Allowing cripples, injured or dead birds to remain in a flock: Fowl will pick on cripples or dead birds in their pens because of the social order and curiosity. Once pecking starts it can quickly develop into a vicious habit.
Nutritional Causes
High Energy and Low Fiber: Extremely high energy and low fiber diets cause the birds to be extra active and aggressive which in turn will make birds to peck others.
Protein Deficiency: Feed lacking protein and other nutrients, particularly Methionine, will also cause birds to pick feathers. "
...and this sxcellent article explains further about feather development pecking etc from MSU extension service:
http://msucares.com/poultry/feeds/poultry_feathering.html
(small excerpt)
..."The most common reason that feathers do not develop is a deficiency of a critical protein constituent (amino acid) from the diet of the birds. The feathers of birds contain high levels of a subunit of proteins called "methionine." Methionine is one of only a few amino acids that contain sulfur, and sulfur is a major constituent of feathers. If bird diets are deficient in any single amino acid, it will most likely be methionine. An adequate level of methionine is required in the diet and a deficiency results in reduced growth and feather development. A methionine deficient bird will tend to eat feathers in an attempt to satisfy a craving for this amino acid. A bird may even pull them from its own body.
Few ingredients used in making poultry diets contain adequate amounts of methionine, so manufactured methionine must be added to the dietary mixture to ensure that the birds receive an adequate amount. All quality poultry feeds are designed to contain adequate methionine and prevent reduced body growth and feather development. However, if additional grains (such as corn) are fed with the complete feed, then the amount of methionine consumed by the bird can be inadequate for providing growth and feather development. Feeding of additional grains with complete poultry feeds is not recommended.
If feathers are developed, but are pulled or broken off, the cause is usually management related. Birds that frequently mate may have an absence of feathers, especially on the backs and heads of hens. The males may also have feathers missing from the breast area. These feathers will grow back after the breeding season is completed. Consult the publication Solutions for Poultry for recommendations for the supplementation of methionine when feeding methionine deficient diets.
If feathers are missing from the abdominal and vent area, the cause is most likely the presence of external parasites such as the northern fowl mite or poultry lice. Infestations of these pests can be controlled by regular sprayings of an approved pesticide like permethrin to the birds. The house and other structures that the birds frequently visit should also be sprayed. This will ensure the elimination of any pests that can reinfest the birds. Several applications at 2 to 3 week intervals will kill pests that hatch from eggs that have been deposited prior to the initial spraying. Consult the publication External Parasite Treatments for approved treatments used on poultry."
. Their poop looks normal though.
