Partial and complete blindness and failure to gain weight were the main signs in most of a herd of feedlot cattle affected with vitamin A deficiency. This chronic affliction was induced by feeding concentrates constituted on the farm with a vitamin A supplement that the manufacturor had mistakenly stated that the level to be added was only one fifth of the needed level. Feeding this deficient diet over months caused the gradual blindness of the herd, with the animals "learning" to adapt relatively unseen. It is interesting that the older female calves were less affected, possibly due to vitamin A production from the corpus luteum. The picture (downloadable file) shows the typical glassy appearence of the eyes and exophthalmus.   Vitamin A deficiency is seen uncommonly, in calves born blind and weak after cows were fed incorrectly, or, as in this case, in feedlot and growing calves (when diarrhea is often seen too). As the liver is a potent store of the vitamin, depletion only occurs after prolonged deficiency in the feed of vitamin A, or its precurser, carotene.