Species Selection Information System

Brassicas are often grazed with no ill effects yet, on occasion, adverse effects do occur. Brassicas have a readily digestible carbohydrate content but are low in fiber so cattle should be provided a fiber source to prevent rumen acidosis and bloat. Limit brassicas to 70% or less of total cattle diet dry matter. Interseeding brassicas with cereal grains such as wheat, rye or oats is recommended to ensure adequate fiber. Adjacent pasture, corn stalks, or palatable hay can provide additional fiber. Cattle should be introduced to brassicas slowly by limiting grazing to a few hours per day for the first week to ten days.  

Strip grazing brassicas is recommended to increase utilization and ensure uniform grazing. Most brassica-related disorders in cattle tend to occur during the first two weeks of grazing while adjusting to the forage. The primary potential disorders are polioencephalomalcia, hemolytic anemia (mainly with kale), nitrate poisoning, and pulmonary emphysema. Other possible clinical disorders include bloat and rumen acidosis, and metabolic problems such as hypomagnesemia and hypothyroidism with goiter. Glucosinates present in brassicas are precursors of irritants that can cause colic and diarrhea.