Effect of different daily doses of gizzerosine on the serum 1,25-dihydroxycholecalciferol concentration in laying hens

1. Five groups of laying hens were treated with different gizzerosine doses (0, 2.5; 5.0; 7.5; 10.0 mg/kg/body weight of gizzerosine) daily over a 21- day period to determine the serum concentrations of 1.25-dihydroxycholecalc iferol (1,25(OH)(2)D), total calcium, inorganic phosphorus and magnesium. B lood samples were taken on days 7, 14, and 21 of the experiment. 2. The concentration of 1,25(OH)(2)D remained unchanged after day 7 in the gizzerosine-treated birds compared to the control group. 3. After 14 days, it was significantly lower in the birds receiving gizzero sine, compared with the control group. 4. On day 21, 1,25(OH2)D concentrations were also significantly decreased i n all 4 gizzerosine-treated groups compared with the control hens. 5. The serum total calcium, inorganic phosphorus and total magnesium concen trations varied significantly, but irregularly during the period of the stu dy.