Comparative Effects of Phytosterols and Plant Oils on the Growth Depression in Chicks Fed Quillaja Saponin

Abstract

To compare the effect of phytosterols (PS) and plant oils on the growth depression due to saponin, seven-day-old chicks were fed experimental diets for 10-12 days. A 0.6% Quillaja saponin in the diet depressed body weight gain, feed intake and gain/feed ratio. PS partly (0.1-0.2%) or completely (0.4 or 0.6%) counteracted the adverse effect of saponin. The effect of cholesterol (CHS) on saponin-fed chicks was compatible with that of PS. The alleviation in growth depression by both sterols was always accompanied by the increase in both feed intake and gain/feed ratio. PS also suppressed the elevated CHS concentrations in the serum and liver induced by the dietary CHS. Corn oil and coconut oil added to the saponin diet improved gain/feed ratio, but they failed to increase feed intake sufficiently. Consequently, the addition of plant oils was less effective than that of PS in alleviating the growth depressing-effect of saponin. Beef tallow, animal fat, showed the same effect on saponin-fed chicks as did plant oils. In addition, the beneficial effect of added corn oil or beef tallow disappeared when metabolizable energy of the diet containing oil or fat was equal to that of basal diet. Thus, the alleviative effect of plant oils seems to be attributed to the increase in the dietary energy rather than to the PS present in oils. In conclusion, increasing feed intake is necessary to improve the growth depression due to saponin.