Influence of Dietary Calcium, Zinc, and Oil upon the in vitro Uptake of Zinc-65 by Porcine Blood Cells

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Abstract
Twenty-four weanling barrows averaging 19 kg were allotted to 6 lots and fed at variable levels of either calcium, zinc, or fat for 16 weeks to determine effects on 65Zn retention by porcine blood cells in vitro. Five milliliters of freshly drawn whole blood were obtained at 2-week intervals and dosed with 200 mµc 65Zn. After incubation under O2 atmosphere at 38° for a 2-hour period, the cells were separated from the plasma and their radioactive zinc content was determined. Average percentage cellular 65Zn uptake per treatment after packed-cell volumes were adjusted to 40 were: basal, 34; basal + 71 ppm Zn, 26; basal + 0.6% Ca, 55; basal + 71 ppm Zn + 0.6% Ca, 28; basal + 5% oil, 34; basal + 0.6% Ca + 5% oil, 51. Dietary calcium increased (P < 0.01), whereas dietary zinc decreased (P < 0.01) in vitro uptake 65Zn throughout the experiment. Added oil exerted no significant effect on 65Zn uptake in vitro. Dietary treatment had no detectable effect on the stable zinc content of these cells. The effect of treatment upon the in vitro uptake of 75Sc, 137Cs, 131I, 60Co, 54Mn, 59Fe, 115Cd, and 64Cu by swine blood cells was also investigated with variable results. Four incidences of parakeratosis were observed in the 8 pigs fed the high calcium-low zinc diets.