The brassica family includes crops used as vegetables, cover crops, oilseeds, and forages. The brassicas used as forage are radish, turnips, kale, and rapeseed. Due to their high water content (>80), brassicas are generally used for grazing. They quickly establish and provide high-quality forage during the fall and winter when perennial forages are dormant.
In the Southeast region, livestock production systems rely on perennial grasses, such as bermudagrass and bahiagrass. These grasses go dormant in early Fall, therefore, a common practice used is to overseed perennial stands with cool-season forages to extend the grazing season. Brassicas are a good option for mixtures when overseeding perennial stands due to their high nutritional value and fast growth. They can also improve soil chemical and physical characteristics, including alleviating soil compaction, promoting rapid plant residue decomposition, and helping to suppress weeds.
Nutritional value
The cattle animal performance of brassicas is very high: 2.5 lbs./head/day or more when grazing brassicas with a small amount of roughage supplementation. Because brassicas have such high quality (high protein amount and low fiber content), when in monoculture, they should be treated similarly to concentrate feeds.
| Crude protein | 20-25% |
| Neutral detergent fiber | 20-25% |
| Acid detergent fiber | 12-20% |
| Total digestible nutrients | 65-70% |
Establishment and management
Brassicas can be planted in monoculture or a mixture of forage grasses and legumes. A no-till drill must be used when overseeding perennial stands with mixtures containing brassicas. Before planting, it is important to graze or mow the forage mass to one or two inches to improve seed-soil contact and avoid competition for resources (e.g., sunlight, and nutrients). The ideal soil pH for brassicas ranges from 5.6 to 6.8, requiring well-drained soils to establish.
When overseeded with bermudagrass, brassicas should be planted in early November and grazed in late January and early February. On prepared seeded, they should be planted in early October and grazed in early December. In monoculture, the kale, rapeseed, and radish seeding rate varies from 4 to 5 lbs. PLS/acre, and from 2 to 3 lbs. PLS/acre for swede and turnip. The seeding rate should decrease when in a mixture.
Fertilization will depend on soil testing, although nitrogen, phosphorus, potassium, sulfur, and boron are the most critical fertilizers for brassicas. It is necessary to apply fertilizers at seeding to give the brassicas a competitive advantage over weeds. Consult your local Extension agent for help.
Proper grazing management will be crucial to allow the species to continue in the mixture, therefore, the recommended stubble height is six to eight inches. Intercropping brassicas with a more fibrous forage as annual cool season grasses can improve digestion and prevent health disorders like bloating and nitrate poising. Brassicas should not exceed 50% of the animal diet to prevent copper and iodine deficiency. Brassicas can cause colic and detrimental gases in equines.
Written by
Luana Zagato, Ph.D. student
Liliane Silva, Forages Specialist
