The Effect of Sodium Zeolite A and Cholecalciferol on Plasma Levels of 1,25-Dihydroxycholecalciferol, Calcium, and Phosphorus in Commercial Leghorns

Abstract

Three experiments were conducted to determine possible mechanisms involved in improving eggshell quality with sodium zeolite A (SZA) (trade name Ethacal® feed component), and cholecalciferol (vitamin D3) by studying the effect of dietary supplementation of SZA and vitamin D3 on plasma 1,25-dihydroxycholecalciferol [1,25-(OH)2 D3], ionic calcium (Ca++), normalized calcium (nCa++), total calcium (TCa), percentage Ca++ to TCa (PCa++), pH, and phosphorus (P). In Experiment 1 (2 × 2 factorial arrangement of treatments), two levels of SZA (0 and .75%) and two levels of vitamin D3 (0 and 175 ICU/kg) were fed. In Experiment 2, five levels of vitamin D3 (100 to 500 ICU/kg) and two levels of SZA (0 and .75%) were fed using a 2 × 5 factorial arrangement of treatments. In Experiment 3, hens were fed two levels of SZA (0 and .75%). Blood samples were collected at 0 (Experiments 1, 2, and 3), 7, 14, and 21 h (Experiment 3) postoviposition (POP).In Experiments 1 and 2, decreasing vitamin D3 decreased plasma l,25-(OH)2 D3 and P. Plasma TCa decreased when 0 ICU vitamin D3 was fed (Experiment 1), but was not affected by vitamin D3 level in Experiment 2. Supplemental SZA had no effect on plasma l,25-(OH)2 D3, TCa, or P in Experiments 1 and 2. In Experiment 3, plasma l,25-(OH)2 D3 and P peaked at 14 h POP, but Ca++ was lowest at 14 h POP. Circadian rhythms for plasma l,25-(OH)2 D3, Ca++, and P were not affected by SZA. There were no significant effects due to dietary SZA on plasma l,25-(OH)2 D3, TCa, Ca++, PCa++, nCa++, pH, or P. It was concluded that SZA did not influence the synthesis of l,25-(OH)2 D3.