Forage brassicas

In recent years the importance of forage brassicas in New Zealand pastoral systems has increased greatly.  Brassica crops can produce a high quantity of high quality feed at times of the year when the performance of ryegrass based pastures is limited (principally a weather driven effect during summer through to winter relating to lack of moisture (summer (and autumn)) or temperature (summer and winter)).  The relative low cost of production of brassicas is also worthy of consideration, being a cheaper option than purchasing supplementary feed.

By providing high quality feed over the months that are traditionally lower in terms of pasture growth and quality (and hence lower animal production and liveweight gain), the overall productivity and output from New Zealand farms have increased.

Brassica crops can also be viewed as part of a pasture based rotation.  As such they are key to re-establishing a high yielding ryegrass pasture following the brassica crop.  For this reason, “run-out’ pastures are chosen to be put into brassicas and then re-sown with a new ryegrass based seed mix.  Providing the soil fertility has been assessed and corrected prior to sowing the brassica crop the improved fertility assists with the establishment of the following grass pasture.

There are a number of brassica options – a brief summary of their use and purpose is given below:
 

Turnip

Turnips are most commonly used as a summer feed and have a wide sowing window over the spring. The number of days from sowing to feeding is fairly constant (depending on the variety) and hence sowing date can be planned to coincide with when the crop is required for stock to eat.
 

Swede

Swedes are used as the main crop winter brassica. They are normally sown in Nov/Dec and have a longer growing season than turnips. Swedes are susceptible to the fungal disease dry rot (usually only a problem in the second crop situation), but if kept free of this disease they produce very high quality feed and high yields.
 

Forage brassica

Forage brassicas offer flexible grazing options, being tolerant of a wide range of conditions. Sown from early spring to early autumn, crops are available from early summer to late autumn. The re-growth potential of forage brassicas is very good and hence multiple grazings are possible providing the crop is managed correctly.
 

Forage rape

Forage rape crops can be sown from early spring through to mid autumn dependant on when the crop is required for feed, and are therefore available from early summer to early autumn. Some varieties can only withstand a single grazing, whereas others demonstrate good re-growth and can be grazed more than once.
 

Forage kale

Forage kale is another winter brassica crop. Resistant to the current known strains of dry rot and clubroot and hence they are a good option for a second brassica crop following swedes or turnips. They vary in terms of leaf to stem ratio and height, and hence varietal choice is important when the crop is to be fed to lambs in particular.
 

For the latest up-to-date information on the growing and management of swede crops, particularly in the second crop situation, please contact your local Farmlands Technical Field Officer or Farmlands store.

Stock feeding recommendations for brassica crops

• Don’t allow stock sudden unrestricted access to a brassica crop
• Feed extra fibre prior to and while grazing brassica crops
• Feed brassicas as part of a balanced diet
• At all times give animals access to water when grazing a brassica crop
• Recognise the potential for stock health problems

For more information or to contact Farmlands Grain and Seed, please call 0800 200 600 or
email: seed@farmlands.co.nz