Effect of Two Levels of Intake of a Vitamin a Depletion Ration on Some Blood Constituents and Deficiency Criteria in the Dairy Calf

The level of feed intake must be considered when studying specific nutrient deficiency symptoms, because biochemical, physiological, and histological changes have been demonstrated to be dependent in many instances upon this factor (8).With respect to the onset of vitamin A deficiency symptoms in the dairy calf, no data were found in the literature on the effect of level of feed intake.However in the ovine, Sapsford (16) reported more rapid rates of decrease of blood plasma vitamin A levels and earlier appearance of morphologically abnormal spermatozoa in rams on a high level of intake of a carotene deficient ration than those for rams on a low intake.In possible contrast, withholding the feed from 25-day-old rats has been reported (12) to result in more rapid rates of decrease of blood plasma vitamin A and vitamin A stores than controls fed a vitamin A-free diet.The present study was concerned with the effect of two levels of intake of a vitamin A depletion ration, one adequate for normal growth and another inadequate, on rates of change of some blood constituents and on terminal physiological and histological alterations in the dairy calf. EXPERIMENTAL A~imals and rations.Twenty one-day old calves (two Ayrshire, two Guernsey and 16 Holstein) were on experiment from February through June, 1952.These calves were either allowed to nurse their dams for a 24-hour period after birth or fed colostrum at the rates of 7.0 lb. for Guernseys and 8.0 lb. for Ayrshires and tIolsteins.Thereafter, they were placed in individual tie-stalls and raised to 35 days of age on a standard limited whole milk, limited dry calf starter and ad libitum hay system (~).Each calf received a 250 rag.oblet of aureomycin for the first 3 days of age, and 14 of the Holstein calves received 100,000 U.S.P. milts of vitamin A from fish liver oil-" for the first and second days of age.