Effect of Level of Ration Intake and Duration of Vitamin A Deficiency Upon Some Biochemical Constituents in Serum, Cerebrospinal Fluid, and Aqueous Humor of Holstein Calves Fed Fixed Carotene Intakes

Abstract

Forty-eight male Holstein calves, averaging 79 days of age and 7.2 ug of vitamin A per 100 ml of plasma, were fed 1 to 2 intakes of a vitamin A depletion ration, 100% to provide an anticipated weekly gain of approximately 10 lb., or 60% of this ration allowance for 1 of 2 durations, 12 wk. or 24-wk., and one of 6 carotene intakes from artificially dehydrated alfalfa, 10-, 20-, 30-, 40-, 50- or 60-gamma per pound of live weight per day. Marked differences between the 60% and 100% intake groups were observed in daily rate of live weight gain, 1.36 vs. 2.08 lb., in heart rate, 74 vs. 88 beats per minute, in the QT electrocardiographic interval, 0.364 vs. 0.314 sees., and in the systolic index, 0.400 vs. 0.378. These differences in the calves fed the 60% level of ration intake, were accompanied by higher concentrations of plasma and liver vitamin A, by slightly lower cerebrospinal fluid pressures, and by an alteration in the protein distribution of serum and cerebrospinal fluid. Slightly lower concentrations of chloride in serum and of sodium and potassium in cerebrospinal fluid occurred in the 60% level of ration intake calves. To maintain equivalent cerebrospinal fluid pressures, calves fed the 60% level of ration intake required 0.74 as much carotene as calves fed the 100% level of ration intake, and to maintain equivalent liver vitamin A stores, 0.86 as much. There was some indication of greater cerebrospinal fluid pressures in the calves fed the 3 lowest carotene intakes for the 24-wk. duration than in comparable calves of the 12-wk. grouping, as well as higher serum magnesium and cerebrospinal fluid sodium concentrations.