The effect of saponin, sterols and linoleic acid on the weight increase of growing rats.

The incorporation of lucerne meal in the diet of chicks prevents normal gains in weight (Alder, 1946; Draper, 1948; Cooney, Butts & Bacon, 1948; Lepkovsky, Shaeleff, Peterson & Perry, 1950; Heywang, 1950; Kodras, Cooney & Butts, 1951 a, b). This effect is attributed to the saponin fraction of lucerne (Peterson, 195oa, b; Heywang & Bird, 1954), which has been shown to be a complex mixture of related substances (Coulson, 1958). However, the sapogenins derived from lucerne saponins have no effect upon the growth of chicks (Potter & Kummerow, 1954). The mechanism whereby mixed lucerne saponins prevent normal gains in weight by chicks is unknown, but the effect can be partly reversed by the concurrent feeding of cholesterol or phytosterols, principally/3-sitosterol (Peterson, 1950 a, b). The growthdepressing effect of lucerne meal is completely overcome by the inclusion of both cholesterol and cottonseed oil in the diet. The commercially available saponin from Quillaja saponaria Molina reduces weight increase in chicks, much as do mixed lucerne saponins (Peterson, 1950 b), and because of its availability has been selected for more detailed study of the effect of triterpenoidal saponins on growth. It has been shown that the normal rate of weight increase in the growing rat is depressed by the addition of Quillaja saponin to the diet, but in rats higher levels of saponin are required to produce the effect than in chicks (Coulson,