Greenleaf Farms

While a  non-essential amino acid for man, molting birds need  high cystine content for renewal of feathers because cystine is necessary for the production of keratin, the prime ingredient that constitutes feathers.  Some medical researchers that it is a lack, or a biological block, of the absorption of cystine, that leads to men's hair loss.

Cystine is found in red peppers, garlic, onions, broccoli, brussels sprout, oats, granola, wheat germ, sprouted lentils & egg yolks, so one easy one to supply cystine is by feeding molting hens,  their own, previously laid, eggs back. Cystine is the stable form of the chemical cysteine.

Tests conducted at the Nebraska Agricultural Experiment Station have shown that the endogenous nitrogen loss among nonmolting hens amounts to about 144 milligrams per kilogram of body weight, and among molting hens, 219 milligrams.

Evidently the molting hen breaks down tissue protein to supply the amino acid cystine for feather growth.

When 145 milligrams of cystine were added to the diet of the molting hen, the endogenous nitrogen loss was reduced to 137 milligrams. The feeding of cystine exerted a protein sparing out of proportion to its nitrogen content, thus indicating its value for feather growth.