Some Ocular Changes and Deficiency Manifestations in Mature Cows Fed a Ration Deficient in Vitamin A

Abstract

Summary 1. Mature cows on a vitamin A deficient ration failed to develop blindness due to constriction of the optic nerve, such as has been reported in calves. 2. A definite papilledema failed to develop in two cows out of six in these experiments. Once the papilledema develops it takes considerable time for it to recede. 3. Mature cows did develop nyctalopia, incoordination, and an edema of the legs on the A deficient ration. 4. The tapetum nigrum and lucidum developed a mottled appearance. 5. When the plasma carotene values receded to a 0.2 to 0.5 microgram level deficiency symptoms usually followed in a short period of time. 6. The fat of a Guernsey cow which died with symptoms of vitamin A deficiency showed the presence of a pigment which was most likely carotene since it was epiphasic between petroleum ether and 92 per cent methyl alcohol.