Risk of bloat
Like other forage legumes, soybean forage may cause bloat in ruminants (Krantz, 2012).
Lupinosis-like toxicity
Mature grain crops of soybean damaged by rain should not be grazed by livestock (particularly sheep) or fed to them, because they may be infected with the fungus Phomopsis, which produces toxins that cause symptoms similar to lupinosis (Mullen, 1999).
Pesticide residues
Some herbicides and insecticides have feeding restrictions for soybean harvested for forage (Krantz, 2012).
Phytoestrogens
Early trials reported that the use of a high proportion of soybean forage was associated with reproduction problems in female rabbits (Kendall et al., 1950). These issues may have been caused by the presence of phytoestrogenic compounds in soybean forage (Magee et al., 1958).