Influence of Inorganic and Organic Dietary Zinc on Its Concentration in Blood Serum, Bones and Hair, and Catalytical Activity of Selected Serum Enzymes in Pigs

Abstract

Rupic. V .. L. Ivandija. S. Luterotti. M. Dominis-Kramaric: lnfiuence of Inorganic and Organic Dietary Zinc on its Concentration in Blood Serum, Bones and Hair, and on Catalytical Activity of SOllie Sen/III En~Yllles in Pigs. Acta vet. Bmo 1997.66: 75-85. The influence of dietary zinc originating from either inorganic or organic source on zincdepleted pigs was investigated. Within the 30 d period preceding the trial. all the animals (German Landrace x Pietrain x Large White x Swedish Landrace weaned crossbreds) were depleted of zinc and divided into three groups. 14 animals in each. During the experimental fattening period (105 d). the control group received no extra zinc. whereas the two trial groups were fed a diet with zinc supplement either as inorganic salt (ZnS04) or metalo-organic chelate (zinc methionate). On average. the respective supplements contained 84.3 mg Zn.kg· l diet and 40.9 mg Zn.kgl diet. Evaluation of the nutritional effects of zinc was based on its concentration in the blood serum, bone and hair. Moreover. the effect of zinc on catalytical activity of alkaline phosphatase. aspartate aminotransferase. alanine aminotransferase and gamma-glutamyltransferase in serum was studied. A decrease of catalytical activity of both aspartate aminotransferase and alanine aminotransferase was found along with signs of parakeratosis on the skin of control animals but no correlation with serum zinc was established. In contrast to this finding. a linear correlation between catalytical activity of alkaline phosphatase and of gamma-glutamyltransferase and serum zinc level was found with the respective correlation coefficients of 0.90 and -0.72. Nutritional efficiency of diet zinc was evidenced by both higher (P < 0.05) zinc level in blood serum. bone and hair and by the state of hepatobiliary tract and bones. and favourable performance results of trial animals compared to controls. None of trial animals suffered from any health disturbances. Progressive parakeratosis appeared. however. in control animals and lasted during the second month of the trial. It was accompanied by deterioration of performance data of the affected animals. Our data suggest that bioavailability of zinc from the chelate was better than of that derived from inorganic salt. particularly in the period of rapid growth. This presumbaly resulted in reduced elimination of zinc. Based on better nutritional efficiency in pigs and on ecological benefits. zinc methionate should be preferred to ZnS04 as a zinc containing diet additive. Growth, pigs. ~illc sulphate. ~illc methionate. bioavailability, nutrition The improvement of body mass gain and carcass quality are among major goals of all pork producers. One of the ways to achieve this is to provide the animals with necessary minerals from the sources of favourable bioavailability. Circulation of zinc and its biological importance in animals (cellular replication. lung tissue CO, release, sexual maturation, wound healing. fertility and reproduction) have been extensively investigated. Zinc is an essential trace element, and it is an integral part of some 300 enzymes (carbonic anhydrase, alkaline phosphatase, alcohol dehydrogenase, RNA and DNA polymerases, 5-nucleotidase, etc.) which take part in protein synthesis, metabolism of carbohydrates and nucleic acids (Mi I ne 1994). It is assumed that Zn derived from compounds with amino acids stimulates