THE EFFECT OF ZINC-DEFICIENCY ON THE OSMO TIC FRAGILITY AND FATTY-ACID COMPOSITION OF ERYTHROCYTES IN GROWING PIGS

The aim of this study was to investigate the effect of zinc deficiency on the fatty-acid composition and osmotic fragility of erythrocytes i n growing pigs. The experiment comprised three groups: a zinc-deficien t group, a pair-fed control group, and an ad libitum control group. Th e ration administered to the zinc-deficient group contained 25 mg zinc /kg on average; rations administered to the pair-fed control group and the ad libitum control group contained 55 and 67 mg zinc/kg, respecti vely, by supplementation with zinc sulfate. The pigs fed the zinc-defi cient ration developed a severe zinc deficiency which was made evident by a significantly reduced activity of alkaline phosphatase (-87 %) c an and zinc concentration (-70%) in serum, as well as by reduced live mass (-15%) in comparison to pair-fed control pigs and signs of zinc d eficiency such as skin lesions. Erythrocytes of zinc-deficient pigs co ntained greater percentages of monounsaturated fatty acids and lower p ercentages of saturated fatty acids and linoleic acid than those of pa ir-fed control rats. Among saturated fatty acids, palmitic acid and li gnoceric acid were the most strongly reduced; among the monounsaturate d fatty acids all the individual fatty acids (18:1 n-7, 18:1 n-9; 20:1 n-9, 24:1 n-9), with the exception of palmitoleic acid, were elevated ; among the polyunsaturated fatty acids, apart from linoleic acid, per centages of docosapentaenoic acid and alpha-linolenic were also elevat ed by zinc deficiency. The osmotic fragility of erythrocytes was signi ficantly reduced by zinc deficiency. When erythrocytes were incubated in sodium-chloride solutions with concentrations of between 0.56 and 0 .65%, the rate of hemolysis was between two-fold and five-fold higher in zinc-deficient pigs than in pair-fed control pigs. In zinc-deficien t pigs, erythrocyte count, hematocrit and hemoglobin concentration wer e tendentially lowered by zinc deficiency. Among the clinical chemical parameters in serum, concentration of total protein was lowered, and that of albumin was elevated, by zinc deficiency.