Abstract

EFFECTS OF INJECTING VITAMIN D3 OR AN ACTIVE METABOLITE IN-OVO ON CHICK EMBRYONIC DEVELOPMENT AND CALCIUM HOMEOSTASIS

Doaa S. Mansour Yakout A. El-Senosi, Mohsen I. Mohamed Magda M. Amer and Mahmoud A. Elaroussi*

ABSTRACT

The relationship between body calcium content and vitamin D3 action in the developing chick embryo is investigated in this study. Two hundred fertile chicken eggs were incubated at 37oC for 21 days and divided into four groups, 50 each. Group 1 (G1) control was injected on day 12 of incubation with 100 μl propylene glycol alone (vechile), group 2, 3 and 4 were injected with the vechile containing 20 ng Cholecalciferol (G2), 20 ng 1,25 dihydroxy vitamin D3 (G3), or 50 ng 1-alpha hydroxy vitamin D3 (G4), following injections eggs were returned to the incubator. Blood, amniotic and allantoic fluids samples were taken from chick embryo at 15, 16 and 17 days of incubation for the determination of calcium, phosphorus, alkaline phosphatase and acid phosphatase. During the same days, whole body embryo and yolk sac were taken, ashed for the determination of calcium and phosphorus content. Data from the present study showed significant rise in serum, allantoic and amniotic calcium concentration during embryonic development in days 15, 16 and 17 day of incubation for all treated groups. Serum calcium level increased from 13.04 ± 0.44 to 14.66 ± 0.39 to 16.06 ± 0.18 for G2 and from 14.24 ± 0.3 to15.98 ± 0.26 to 17.6 2± 0.30 for G3 and from 12.10 ± 0.39 to 13.02 ± 0.13 to 13.94 ± 0.11 for G4, respectively. Similar increase in phosphorus, alkaline phosphatase and acid phosphatase was also found for all groups. Data also showed that significant accumulation of calcium and phosphorus content occurred in both whole embryo and yolk sac at days 15 and 16 that reached maximal values at day 17 of incubation. In conclusion, the results reported in the present work indicate that vitamin D3 or its metabolite treatments result in a gradual and significant rise in whole embryo and yolk sac calcium content, serum levels of calcium and phosphorous during the development of the chick embryo. They also emphasize the regulatory potential of vitamin D3 on the metabolism of both elements during embryonic development of chicken. Collectively, the present data endorse the ability of supra physiological doses of different forms of vitamin D3 to accelerate both calcium and phosphorous mobilization from the egg shell to the developing chicken embryo.

Keywords: Chick embryo, vitamin D3, body and yolk calcium content, serum calcium, alkaline phosphatase, acid phosphatase.