Reevaluation of the Minimum Vitamin A Requirement of Holstein Male Calves Based Upon Elevated Cerebrospinal Fluid Pressure

Forty-one male Holstein calves whose average age was 60 days, live weight 74kg and plasma vitamin A concentration 8.4 μ g/100ml were fed a vitamin A depletion ration plus one of five daily vitamin A acetate intakes equivalent to 4, 12, 16, 64 or 256 μ g of retinol per kilogram of live weight for 16 weeks. Daily ration consumption averaged 3.0 kg/day, and live weight increased .81kg/day. The incidence of diarrhea, the number of treatments for diarrhea, and the number of calves exhibiting convulsions were greater in the calves fed the lowest vitamin A intake of 4 μ g. Average plasma vitamin A concentrations increased .8 μ g/100ml for each 10% increase in vitamin A intake and terminal values increased .9 μ g/ 100ml. Cisternal cerebrospinal fluid (CSF) pressures were maintained at a geometric mean of 68mm of saline at vitamin A intakes greater than 29 μ g per kilogram of live weight. For each 10% decrease in vitamin A intake below the 29 μ g intake, CSF pressure increased by 8.6%.