Comparison of Ethanol‐Extracted and Unextracted Crownvetch Forage Fed to Weanling Meadow Voles 1

The potential effects of adverse constituents in crownvetch ( Coronilla varia L.) forage on animal response were assessed using the weanling meadow vole ( Microtus pennsylvanicus ) as the test animal. ‘Chemung, ’ ‘Emerald,’ and ‘Penngift’ crownvetch were harvested at the early‐bud and late seed‐set stages during two growing seasons. Crownvetch forage extracted with ethanol and unextracted forage were incorporated into diets supplemented with adequate levels of protein, carbohydrate, vitamins, and minerals and fed to weanling meadow voles. Of 72 voles fed unextracted crownvetch diets, 46 died within 6 days, and most of the remaining voles lost weight. Deaths and weight losses were greatest on the mature crownvetch diets, with more deaths occurring from the 1969‐harvested forage than from that of 1971. The deleterious substance was apparently removed by ethanol extraction of the forage as shown by the death of voles fed control diets to which the ethanol extract was added. Weight gains and dry matter consumption of voles fed diets prepared with ethanol‐extracted forage were equivalent to those of the voles fed control diets containing purified cellulose.