Dried brewers' yeast has nutritional importance as a feed
supplement because it has a high protein content and be
cause it supplies most, if not all, of the B vitamins. Brewers'
yeast has been studied for its effect on various rations as
a protein supplement, as the sole source of protein, as a B
vitamin supplement and as the sole source of B vitamins.
However, the reports of these studies in the literature are
both scattered and contradictory. Osborne and Mendel ('19) fed rats on brewers' yeast as
the sole source of protein. Those on 40% levels were main
tained with a normal growth rate for more than a year, but
those on a 30% level showed rather poor growth during this period. Nelson, Heller and Fulmer ('23) succeeded in rear
ing three generations of rats on a diet containing 45% dried
brewers' yeast; however, the growth of the offspring was al
ways slightly below normal and lactation was poor. Sure
('46) fed a brewers' yeast at 30% and 40% levels and noted
that the growth, reproduction and lactation performances in
three consecutive generations of rats were comparable to
those of rats on a diet containing 15% purified casein. In
subsequent studies with another type of brewers' yeast, how-