Experimental pathology of dairy calves ingesting one-third the daily requirement of carotene.

At 53 days of age, 30 male Holstein-Friesian calves were divided into 2 equal groups and fed for a 17 week period a ration containing either 15 µg (deficient) or 150 µg (control) of carotene per 0.45 kg of live-weight per day. Twelve of the 15 deficient calves had an elevated cerebrospinal fluid pressure (GSFP), above 200 mm of saline. The mean GSFP of the deficient group was 3 times that of the control group. Fourteen of the 15 deficient calves had varying degrees of papilledema and 6 had hypophyseal cysts. The main parotid duct (Stensen’s duct) was affected by squamous metaplasia, in all the deficient calves. The mean plasma carotenoid and vitamin A concentrations for the control calves were 5 times higher than the deficient animals. Liver carotenoid and vitamin A concentrations were markedly lower in the deficient calves and correlated well with elevated CSFP, papilledema and parotid duct metaplasia.