EFFECT OF DIETARY SAPONIN ON EGG CHOLESTEROL LEVEL AND LAYING HEN PERFORMANCE

Abstract

A feeding trial was carried out for five 28-day periods with diets containing 0.0, 0.04, 0.2 and 0.4% of saponin (Sarsaponin) in either the presence or absence of dietary cholesterol to study the saponin-cholesterol interaction and also to determine the effects on the levels of yolk cholesterol and the performance of single-comb White Leghorn laying hens (44 wk of age). No significant differences were found in the levels of egg yolk cholesterol; however, egg production and feed intake were reduced by feeding saponin. These adverse effects on the layer performance were counteracted or completely disappeared when 0.5% cholesterol was fed simultaneously to the laying birds. Egg yolk cholesterol contents were raised by dietary cholesterol but were not influenced by the dietary presence of saponin. In the second trial, layers were given a dose of 14C-cholesterol emulsified in corn oil with and without 0.48 g saponin in order to determine the specific effect of saponin on dietary cholesterol absorption and deposition into egg yolk. Dietary saponin increased the excretion of 14C-cholesterol from 8.6 to 65.8%, decreased egg deposition from 31.5 to 16.6% and decreased serum radioactivity by 39.2%. Thus, it was concluded that dietary saponin reduced cholesterol retention and transfer of dietary cholesterol to egg yolk, but failed to lower cholesterol content in egg yolk. Key words: Saponin, egg cholesterol, 14C-cholesterol, laying hens