Use of slow-release pellets to administer calcitriol to avian embryos: Effects on plasma calcium, magnesium, and phosphorus

Abstract

Calcitriol (1,25-dihydroxycholecalciferol) was administered to embryos of domestic fowl by slow-release pellets inserted into eggs on Day 10 of incubation. Mortality among embryos receiving 10 pg/day was no different from that of controls, but mortality among embryos receiving 100–1000 pg/day was elevated in later stages of incubation. Concentrations of calcium in plasma did not vary over the course of incubation among surviving embryos receiving carrier, but concentrations of magnesium and inorganic phosphorus declined with time. All doses of calcitriol elicited increases in plasma Ca and Mg on Day 12, and embryos may have responded also with a dose-dependent hypophosphatemia. The increases in plasma Ca and Mg were not sustained for the remainder of incubation, but the hypophosphatemia seemingly was of longer duration. This study demonstrates a new procedure for administering hormones to avian embryos and reveals that embryonic chickens respond in the expected manner to very small quantities of calcitriol.