Bloat
Grazed or fresh alfalfa at vegetative or mid-bud stage may cause bloat in sheep and cattle. This problem may be alleviated by restricting access to alfalfa or by feeding sheep and cattle before they come into the sward. Supplementing cattle and sheep with grass, cereal grains or anti-foaming agents (such as poloxalene) can alleviate this problem (Frame, 2005). Access to anti-bloating agents (drenching, addition to the water supply, rumen capsules, spraying) is essential in intensively grazed situations (Cook et al., 2005). Forage cut at flowering time and dried in the field rarely causes bloating (Duke, 1983).
Photosensitization
Cases of photosensitization have been reported in cattle and sheep. In male sheep, it can result in pizzle rot and enterotoxemia (Cook et al., 2005).
Phytoestrogens
Alfalfa contains phytoestrogens that are reported to reduce conception rates in cattle and sheep fed alfalfa prior to mating (Frame, 2005). The estrogen content varies among genotypes, but may increase in leaves due to attacks of parasites and fungi that are often prevalent in the autumn (White, 1982).
Saponins
Saponin content in alfalfa forage may have adverse haemolytic effects on livestock and reduce growth and egg-production in poultry (Munro, 2009). However, it also gives the plant resistance to pests (Tava et al., 1993).