Effects of Addition of Magnesium, Tocopherol, and Cod Liver Oil to a Whole Milk Diet on Some Biochemical Constituents in Serum, Soft Tissue, and Bone of Calves

Forty-eight male Guernsey calves, approximately seven days old, were fed a basal ration of whole nfilk plus required minerals, except magnesium, vitamin A and D, and ehlortetracycline.Added per 100 lb.live weight per day to this ration, separately and in all possible combinations (2 :~ factorial design), were magnesium (Mg), at 2.5 g.; D,L-atoeopheryl acetate (T), 200 rag.; and cod liver oil (CLO), 1 oz.In anticipation of high mortality, eight calves were fed the basal ration, 12 the basal plus CLO, and eight the basal plus Mg plus CLO; this was in contrast to only four calves on the other treatments.None of the calves fed the basal ration died or exhibited signs of tetany characteristic of hypomagnesemia; however, mortality was high in the latter two groups, six and four calves, respectively.The results presented below were based upon four calves per treatment group which survived the 28-wk.experimental period.The addition of Mg resulted in a greater incidence of scours, higher terminal serum inorganic phosphorus, nmgnesium, and total toeopherol concentrations, lower heart and skeletal musele calcium, greater heart and skeletal nmscle magnesium (only in the absence of T from the ration), and lower calcium and higher magnesium in the bone ash.The addition of CLO produced a variety of effects : lower live weight gains and greater incidence of scours (only in the absence of T from the ration), longer P-R and Q-T electrocardiographic intervals as well as systolic indexes~ greater concentrations of potassium and vitmnin A in the serum, lower serum concentrations of magnesium, total tocopherol~ and earotenoids, and greater whole blood urea levels.