With farmers trying to maximise homegrown feed, Germinal’s Dr Mary McEvoy explains how and why to use forage brassica crops.
“Homegrown forage will help to bridge feed gaps on farms this winter,” says Dr McEvoy.
“When we talk about brassicas, there are so many varieties – from leafy kales and forage rapes to root crops. There will usually be a brassica to suit your feeding goals – whether summer grazing, autumn grazing or to support outwintering systems.”
Benefits of forage brassica crops
“You can use brassicas to extend your grazing season and increase output per hectare. This reduces labour, machinery and housing costs during the winter and help lower any associated animal health risks if you choose to outwinter.”
Brassicas also act as a valuable break crop ahead of pasture renewal and will rejuvenate soil health.
Brassica dry matter yields
Brassicas can deliver a kilo of dry matter (DM) for a cost of 10-14 cents and some catch crops can be ready to graze two months after sowing.
For example, stubble turnips can be sown in May and grazed just eight weeks later; providing DM yields of around 5-7.5 tonnes/ha, with 10-13 ME and crude protein at 16-17%.
Other popular brassica crops include Maris Kestrel kale, which is very winter hardy and suitable for overwintering, with DM yields of 10-14 tonnes/ha.
Triumph swedes are often used to support lamb and ewe condition over winter. Their high DM yield and ME value between 12-14 MJ/kg means they support high stocking rates on small areas of land.
Fodder crop production and selection guide
| Crop & variety | Sowing time | Seeding rate (per acre) | Time of utilisation | Estimated DM yield (t DM/ha) | DM% | CP% | Metabolisable Energy (MJ/kg DM) |
| Kale: Maris Kestrel | May- June | 2.50-3.00 kg* | November- February | 10-12 | 14-16 | 16-18 | 12.5-13.5 |
| Hybrid brassica: Redstart | May- August | 3.50-4.00 kg | June- February | 6-8 | 12-14 | 18-20 | 10-11 |
| Forage rape: Stego | July- August | 3.50-4.00 kg | October- February | 4-6 | 12-14 | 18-20 | 10-11 |
| Swede: Triumph | May- June | 400 g | November- February | 10-12 | 10-12 | 10-12 | 12.5-13.5 |
| Leafy turnip: Appin | April- September | 2.00-3.00 kg | June- February | 3-5 | 8-10 | 18-20 | 10-11 |
Note: If broadcasting, increase the seeding rate to 4.00 kg/acre
“I advise farmers to calculate when they will need additional forage, and work backwards from that point to establish brassicas at the right time for them.
“As a general guide, I would recommend end of June at the latest for autumn and winter grazing of kale, but a quick catch crop can be sown until late August,” Dr McEvoy concludes.
For more information, please view our guide on managing forage brassicas.