THE EFFECT OF DIETARY MAGNESIUM LEVEL ON THE MAGNESIUM METABOLIZABILITY IN LAYING TSAIYA DUCK AND LEG HORN HEN

The study was undertaken to determine the effect of various levels of dietary magnesium on the metabolizability of magnesium in laying Tsaiya ducks and Leghorn hens. Twenty-five Tsaiya ducks and 25 Leghorn hens were raised in individual cages. The basal diet was mainly consisted of corn starch and isolated soybean protein. At the beginning of the experiments, birds were fed the basal diet added with 500 mg/kg Mg (1070 mg/kg in total by analysis) for 10 days in order to make the birds adapt to the new diet. Then, they were randomly divided into five treatments with five birds for each treatment and fed the experimental diets containing 690, 1070, 1690, 2150 or 2380 mg/kg Mg for 21 days and during the last five days excreta were collected. The experiment was repeated three times each at the age of 25, 31 and 36 weeks. The metabolizability of magnesium in the diet was determined by the indicator method. The metabolizabilities of magnesium for Tsaiya duck and Leghorn hen were 59.9% and 62.5%, respectively as the diet contained 690 mg/kg magnesium, and were significantly decreased (p<0.05) to 39.7 and 30.7%, respectively when the dietary magnesium content was increased to 2380 mg/kg.