Hybrid brassicas offer new possibilities

Fodder crop feeding options have been increased with the development of hybrid brassicas, writes Ray Morrison, Morton’s Technical Manager.

Historically forage crops have been regarded as a feed option for livestock in the winter/early spring feeding period. Their high yield potential, nutritional quality and winter hardiness make them an attractive choice for farmers wintering stock outdoors.

Traditional crops of choice still include kale, forage rape, swedes, stubble turnips and fodder beet. However, the development of hybrid brassicas is a significant breakthrough for forage crops. The two most common hybrids are Redstart and Tyfon. Redstart is a cross between kale and forage rape, and Tyfon is a cross between a stubble turnip and a Chinese cabbage.

Because they are hybrids they are very vigorous and grow rapidly. They also have significant regrowth ability. If they are not severely damaged or poached in a first grazing they will grow rapidly again to give a second and possibly third grazing. This will not happen in the winter because of low temperatures and severe grazing conditions, but it is a trait that can be utilized in summer and autumn. In addition hybrid brassicas have a very high nutritional value both in terms of energy and digestible proteins.

Many grassland farms suffer a dip in yield and quality from their swards in mid-summer. This can impact on finishing lambs, cattle and milk production. Hybrid brassicas sown in late April/early May are ideal to bridge this forage deficit. These crops are fit to be grazed 8 to 10 weeks after sowing. They have a yield potential of 4 to 6tDM/ha and this is of extremely palatable material. After grazing the crop can be fertilized and grown again for a mid-October grazing or deferred for winter forage. Depending on management a similar yield to the first grazing is achievable.

Alternatively these crops can be used as a nurse crop to new reseeds. The new leafy, highly digestible grass and hybrid combination is “rocket fuel” for finishing lambs and the intensive grazing management demanded by this crop creates an ideal sward in the new reseed. These crops are block grazed in rotation having been divided into 3 or 4 sections. Lambs get to required weights quicker and this helps to prevent the need to finish with concentrates or sell as stores.

Key points for successful use of hybrid brassicas

1. They are small seeds so a fine firm seed bed is essential.

2. A vigorous growth habit generally out-competes weeds.

3. It is critical to use adequate N and P to realise their yield potential.

4. As with all brassicas trace element supplementation is critical.

5. When feeding all brassicas, provide a fibre source to the animals; this will not be necessary where they are sown with grass.

6. Overgrazing or grazing in very difficult conditions will affect regrowth of the crop.

7. With good management hybrid brassicas can be used for several grazings during the summer season or for single grazing as a dedicated winter feed.

8. Key varieties are Redstart forage brassica and Tyfon stubble turnip.

Hybrid brassicas can allow several grazings during the summer to provide a high energy and highly digestible feed.

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