THE EFFECT OF ZINC-DEFICIENCY ON FATTY-AC ID COMPOSITION OF VARIOUS TISSUES IN THE GROWING PIG

The present study investigated the effect of zinc deficiency on fatty acid composition of total lipids, phospholipids and neutral lipids of liver, muscle, back fat and serum in the growing pig. Additionally, co ncentrations of total lipids and cholesterol were determined in liver, muscle and back fat as well as concentrations of cholesterol, triglyc erides and phospholipids in serum. The experiment included a zinc-defi cient group, a pair-fed control group and an ad-libitum control group. The zinc-deficient group received a ration with an average zinc conce ntration of 25 mg/kg, rations for pair-fed and ad-libitum control grou p contained 55 mg/kg resp. 67 mg/kg zinc. Severe zinc deficiency in th e zinc-deficient pigs was evident by a large decrease of activity of a lkaline phosphatase (- 87 %) and serum zinc concentration (- 70 %) and by reduced final live mass (- 15 %) compared with pair-fed control pi gs. The most pronounced effects of zinc deficiency on fatty acid compo sition occurred in monounsaturated fatty acids, which were elevated by zinc deficiency in total lipids, phospholipids, and neutral lipids of liver, in total lipids and phospholipids of serum and in total lipids of muscle. Elevated levels of monounsaturated fatty acids suggest an elevated Delta 9-desaturation in zinc deficient pigs. In contrast, it is likely that Delta 6- and Delta 5-desaturation was not influenced by zinc deficiency because a reduced level of arachidonic acid occurred only in liver total lipids and phospholipids but not in other tissues. In serum, zinc deficiency reduced level of linoleic acid in all the l ipid fractions. Concentrations of total lipids and cholesterol in tiss ues were not influenced by zinc deficiency. Concentrations of lipids i n serum were lower in zinc deficient pigs by 10 % to 20 % compared wit h control pigs; however, this effect was not statistical significant.