Choline
Choline forms part of the chemical substances that enable electrical pulses to pass between nerve endings. It is produced from the amino acid methionine. Signs include poor growth and reduced litter size. At one time it was thought that this vitamin was involved in splay-legged piglets but scientific evidence has not supported this and when it has been added to diets in cases of outbreaks there has been no response. A deficiency would be unusual.