Effect of dietary supplementation of trace elements on blood chemistry and selected immunological indices depending on the age of broiler chickens

This study was performed to determine the effects of dietary supplementation of Cu, Zn, Fe, Mn and Se on some haematological, immunological and enzymatic indices in blood of broilers at the age of 21, 35 and 42 days. The basal diets (BDs) for Groups 1 and 2 were supplemented with the equivalent amounts of trace elements in an inorganic form (Cu sulphate 5 mg·kg-1 DM, Fe sulphate, Zn oxide, Mn oxide 50 mg·kg-1 DM), however sodium selenite or selenized yeast (Sel-Plex) were given at a dose of Se 0.3 mg·kg-1 DM, respectively. Groups 3 and 4 received the same BD´s but with the substantially reduced amount of supplemented nutrients in the organic “proteinated” form (Bioplex Cu 2.5 mg·kg-1 DM, Bioplex Fe, Bioplex Zn, Bioplex Mn 10 mg·kg-1 DM), except for selenium that was given at a dose of Se 0.3 mg·kg-1 DM as sodium selenite or Sel-Plex, respectively. The supplementation of restricted doses of trace elements in the organic forms into the diet did not affect studied haematological, immunological, enzymatic indices. At the age of 21 days, the activity of GSH-Px was significantly higher in the groups supplemented with sodium selenite later no differences due to the administered form of Se were found. This indicates that the GSH-Px activity reached a plateau in all groups of broilers at the 21, 35 and 42 day, except for GSH-Px activity in the groups of birds supplemented with selenized yeast on day 21. In Addition, significant age dependent changes were observed in blood chemistry, but the different treatments did not influence these changes. Base on our results, the doses of organic forms of trace elements supplemented into the diets for poultry can be restricted to 50% (Bioplex Cu) and 20% (Bioplex Fe, Bioplex Zn and Bioplex Mn) without influencing the blood chemistry of broilers.