5Puvogel G,Baumrucker C,Blum J W. Plasma vitamin A status in calves fed colostrum from cows that were fed vitamin A during late pregnancy[J].Journal of Animal Physiology and Animal Nutrition,2008,(05):614-620.doi:10.1111/j.1439-0396.2007.00757.x.
6Joyce V D,Edward G C. Blindness Caused by Hypovitaminosis A in Feedlot Cattle[J].Canadian Veterinary Journal-Revue Veterinaire Canadienne,1988.925-927.
7Eillen D D,Theller C,Smith S. Temporally-regulated retinoic acid depletion produces specific neural crest,ocular and nervous system defects[J].Devel,1997.3111-3121.
8Leaold H W,Mills J H L,Huston K. Retinal dysplasia and internal hydrocephalus in a shorthorn calf[J].Canadian Veterinary Journal-Revue Veterinaire Canadienne,1974,(02):34-38.
9Spratling F R. Experimental hypovitaminosis A in calves[J].Clinical and gross post mortem findings[J].Veterinary Record,1965.1532-1542.
10Slatter D H. Fundamentals of Veterinary Ophthalmology[M].London:WB Saunders,1981.579-580,47-648.
