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

Abstract

Summary Forty-eight male Guernsey calves, approximately seven days old, were fed a basal ration of whole milk plus required minerals, except magnesium, vitamin A and D, and chlortetracycline. Added per 100lb. live weight per day to this ration, separately and in all possible combinations (2 3 factorial design), were magnesium (Mg), at 2.5g.; d,l-α-tocopheryl acetate (T), 200mg.; and cod liver oil (CLO), 1oz. 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, magnesium, and total tocopherol concentrations, lower heart and skeletal muscle calcium, greater heart and skeletal muscle 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 vitamin A in the serum, lower serum concentrations of magnesium, total tocopherol, and carotenoids, and greater whole blood urea levels. Also, the addition of CLO resulted in marked effects on many of the biochemical constituents determined in heart and skeletal muscle as well as liver, eg., for muscle, lower concentrations of dry matter, ash, phosphorus, magnesium, potassium, creatine, nitrogen, and tocopherol, and greater contents of calcium and sodium. CLO, also, caused greater bone calcium and lower magnesium content. As was anticipated, the addition of T to the ration largely offset the effects of the addition of CLO. A notable exception was the absence of any effect of T on the greater electrocardiographic intervals resulting from CLO.