Variation in S-methyl cysteine sulphoxide concentration with harvest date in forage rape (Brassica napus)

Patterns of variation in glucosinolate concentrations of three forage rapes (Brassica napus L) over a 14-week period suggest that a high frequency of sampling the crop is necessary to determine when animals are likely to have a minimum intake of such anti-metabolites (Macfarlane Smith and Griffiths 1988). A study of S-methyl cysteine sulphoxide (SMCO), which causes anemia in animals (Greenhalgh 1969), in the same three rapes showed similar variation in concentration with time in both the leaf and stem. However, for any given sampling date, SMCO concentrations were very similar throughout the plant. Variation in nitrogen concentration within the plant did not follow the same pattern as SMCO.