Various Levels of Calcium and Phosphorus Diets in Response to ۱, ۲۵ – Dihydroxycholecalciferol in Laying Hens

The effect of ۱,۲۵-dihydroxycholecalciferol [۱,۲۵-(OH)۲ D۳ ] supplementation on laying hen diets was evaluated using diets high and low in Ca (۳.۰% and ۱.۸% ) and high and low in P( ۰.۵۲% and ۰.۳۳% ). Since two levels of ۱,۲۵- (OH)۲ D۳ supplementation (۰ and ۵ µg/kg diet ) were applied, the experiment was a ۲ X ۲ X ۲ factorial arrangement in a com-pletely randomized design using nine individually housed hens per each ۸ treatments (۷۲ in total). The hens were fed the diets for ۲۸ days and records were kept on body weight, egg production, feed intake, egg weight, and egg specific gravity. At the end of the ex-periment, the hens were bled for plasma Ca and P determination and after being eutha-nased the left tibia removed for bone ash measurement. The corn-soybean meal based diet contained ۰.۱% Cr۲O۳ as an indicator for determining Ca, P and phytate phosphorus re-tention at ۱۴ and ۲۸ days. ۱, ۲۵-Dihydroxycholecalciferol supplementation had no effect on hen weight, egg production or feed intake. However, large increases in egg specific gravity were obtained when ۱, ۲۵-(OH)۲ D۳ was fed to hens receiving the low Ca diet. All of the treatments had significant effects on bone ash. The greatest effect of ۱, ۲۵-(OH)۲ D۳ on bone ash was obtained in those hens fed the high Ca and P diet that was then supple-mented with ۱,۲۵-(OH)۲ D۳ (۴۹.۳% vs ۵۳.۹% bone ash). At day ۱۴, the high Ca diets de-creased phytate P retention while at d ۲۸ the high P diets decreased phytate P retention.

Keywords:

Phosphorus , Calcium , ۱ , ۲۵-dihydroxycholecalciferol , Phytate phosphorus