Review of rapeseed meal in animal nutrition: ruminant animals [Dairy cattle]

During recent years, world literature in this area has increasingly dealt with the assessment of low glucosinolate RSM‐type (LGRSM). Generally, the LGRSM‐types show clear advantages over the high glucosinolate RSM‐types (HGRSM). Acceptibility of concentrates to dairy cattle may be influenced negatively by increasing RSM of commercial Canadian HG‐type beyond 15%. LGRSM seems to be acceptable up to at least 20% of the concentrate mixture. LGRSM‐type meal of cv. Candle may possibly still be accepted at higher levels. There are indications of a higher nutritive value of the LG vs the HGRSM types. Candle has been found to be as good as, if not better than, Tower RSM. HGRSM of European origin at a level of 15–20% of the concentrate seems to decrease milk production and to influence milk composition negatively. Canadian‐type LGRSM feeding at a level of 25% of the concentrate does not seem to be harmful to dairy cattle. Inclusion of 34% LGRSM lowered feed intake and milk yield. Higher milk yields are indicated when Candle is included, in comparison to Tower. Only a limited influence on milk composition (protein, fat, solids—nonfat) has been reported to result from RSM‐feeding. Both HG‐ and LGRSM increase milk SCN− and decrease milk‐I contents, the milk‐I, however, to a minor extent. A minute part of the OZT has been found to be carried over into milk resulting in levels much below the safe level for human consumption. Inclusion of “gums” at levels up to several times the amount corresponding to normal production has not been found to impair production traits of dairy cattle or growing cattle. Microbiological degradation of RSM in the rumen can be minimized by formaldehyde treatment, which has been reported to increase milk production. Rapeseed and rapeseed expeller seem to be prospective fat and protein sources to dairy cattle, especially in rations low in crude fat (