Istražen je učinak aplikacije 1,25-dihidroksikalciferola na razinu magnezija u serumu pjetlića lake pasmine. Istraživanja su obavljena na 78 pjetlića, u tri odvojena pokusa. Prvi pokus imao je za cilj utvrditi učinke jednokratne aplikacije visokih doza kalcitriola, drugi pokus učinke ponavljanih niskih doza kalcitriola, a treći učinke jednokratne visoke doze kalcitrola i 48-satnog gladovanja. Koncentracija magnezija određena je u serumu pomoću automatskog analizatora. Visoke doze kalcitriola dovele su do smanjenja razine magnezija u serumu i kod stresa uzrokovanog gladovanjem i pri odsutnosti stresa, dok ponavljanje niskih doza nije dovelo do značajnih promjena. Iz rezultata je vidljivo kako visoke doze kalcitriola pri optimalnim količinama minerala u hrani dovode do smanjenja razine magnezija u krvi. Potrebna su daljnja istraživanja kako bi se utvrdio učinak kalcitriola na metabolizam magnezija u stanjima promijenjene opskrbe peradi magnezijem i utvrdila važnost stimulativnog učinka vitamina D na intestinalnu resorpciju magnezija.We investigated the effect of the application of 1.25-dihydroxycalciferol on the level of magnesium in the serum of light breed cockerels. Investigation was carried out on 78 cockerels, in three separate experiments. The first experiment aimed to determine the effects of single dose administration of high doses of calcitriol, the second experiment aimed to determine the effects of repeated low doses of calcitriol and the third the effects of a single high dose calcitrol after 48-h fast. The magnesium concentration was determined in the serum using an automatic analyzer. High doses of calcitriol led to reduced levels of magnesium in the serum and in stress induced fasting, while low doses did not lead to significant changes. The results show that high-dose calcitriol, when using mineral balance diets, leads to reduced levels of magnesium in the blood. Further research is needed to determine the effect of calcitriol on the metabolism of magnesium during impaired supply of poultry with magnesium and to determine the importance of the stimulatory effect of vitamin D on the intestinal absorption of magnesium
