Effects of Serum Vitamin A Level on Tapetum in Japanese Black Cattle Eye

The relationship between serum vitamin A level and tapetum reflection was investigated using ultraviolet imaging. The tapetum was obtained from eyes of slaughtered cattle in which the serum vitamin A level was below 50 IU/dl. The tapetum reflection was examined in the tapetum lucidum, tapetum nigrum, and optic disc. For each part, the tapetum reflection decreased with increasing serum vitamin A level. A high tapetum reflection value might represent the bleached tapetum symptom that occurs because of the low serum vitamin A level.