ß-Carotene only occurs in plants. Leafy grass, alfalfa and carrots are rich sources of  ß-Carotene. Conserved forage however, has variable  and unpredictable ß-Carotene content. The ß-Carotene content of corn silage is negligible (figure). Field survey results (1999 – 2004) show that  grass silage is an unpredictable source of ß-Carotene. This is very much related to the crop and the conservation technique. ß-Carotene content in forage (Survey results, DSM 1999 – 2004)