Riboflavin (B3)
"Many tissues may be affected by riboflavin deficiency, although the epithelium and the myelin sheaths of some of the main nerves are major targets. Changes in the sciatic nerves produce “curled-toe” paralysis in growing chickens. "
"A 100-mcg dose should be sufficient for treatment of riboflavin-deficient chicks, followed by incorporation of an adequate level in the diet. However, when the curled-toe deformity is longstanding, irreparable damage occurs in the sciatic nerve, and the administration of riboflavin is no longer curative.
Most diets contain up to 10 mg of riboflavin/kg. Treatment can be given as two sequential daily 100-mcg doses for chicks or poults, followed by an adequate amount of riboflavin in feed."
Pyridoxine (B6)
"Young chicks may show nervous movements of the legs when walking and often undergo spasmodic convulsions, leading to death. During convulsions, the chicks may run about aimlessly, flapping their wings and falling with jerking motions."
Thiamine (B1)
"Poultry are also susceptible to neuromuscular problems, resulting in impaired digestion, general weakness, star-gazing, and frequent convulsions.
Polyneuritis may be seen in mature birds ~3 wk after they are fed a thiamine-deficient diet. As the deficiency progresses, birds may sit on flexed legs and draw back their heads in a star-gazing position. Retraction of the head is due to paralysis of the anterior neck muscles. Soon after this stage, chickens lose the ability to stand or sit upright and topple to the floor, where they may lie with heads still retracted."
"In otherwise adequate diets, deficiency is prevented by supplements of thiamine up to 4 mg/kg."
Vitamin E
"deficiency accompanied by sulfur amino acid deficiency results in severe muscular dystrophy in chicks by ~4 wk of age. This condition is characterized by degeneration of the muscle fibers, usually in the breast but sometimes also in the leg muscles."
"Oral administration of a single dose of vitamin E (300 IU per bird) usually causes remission." I stand corrected. I could have sworn it was 400 IU, but apparently, I misremembered. EDT: or they could have revised it. There are a few things I don't remember being in this article.
https://www.merckvetmanual.com/poul...ement-poultry/vitamin-deficiencies-in-poultry