Coumestrol in alfalfa as a factor in growth and carcass quality in lambs.

E STROGENIC materials (specifically diethylstilbestrol), when either fed or implanted subcutaneously, have been clearly shown to improve weight gains and gross efficiency of feed conversion in sheep and other domestic animals (N.R.C., 1960). Similarly, considerable data attest to the presence of materials having estrogenic activity in forages (Pieterse and Andrews, 1956a, b; Bate-Smith et al., 1953; Bickoff et al., 1957; Kitts et al., 1959a; Moule et al., 1963). Potency of these "plant estrogens" has been shown to vary with species of plant, time of cutting, location, fungus infestation and perhaps other factors (Legg et al., 1950; Kitts et al., 1959b; Bicko~, 1961; Hanson et al., 1965). Certainly there are well-documented instances of levels of plant estrogenicity sufficient to affect fertility in animals (Bennetts et al., 1946; Engle et al., 1957; Fox et al., 1959; Moule, 1961). Considered together, these separate items suggest that use may be made of the developing knowledge of estrogen activity in plants in the business of livestock production: either in avoiding interference with reproduction, or conversely in the stimulation of growth. The experiments reported herein were designed to test the effects of feeding dehydrated alfalfa meals having high or low estrogenic activities, or fractions of such meals, upon growth and carcass characteristics of lambs.