Forage rapes have been a valuable tool for temperate pasture systems in Australia for many years. They provide high volumes of extremely high quality feed at a time of year when the feed quality of pasture is starting to decline and this may coincide with when livestock are not quite in a condition for selling – lambs especially.
A lot has been learnt about how to best manage and utilise forage rape crops to minimise animal health complications and at the same time, achieve the greatest animal productivity returns possible from such a high quality feed.
Forage rapes offer the added benefit of being a valuable tool in a renovation programme. Because of the time of year that a forage rape traditionally gets sown, it allows for a good ‘knockdown’ herbicide to kill off all weeds that are actively growing prior to seed set.
Forage rape also offers the potential for a disease break crop due to its natural bio-fumigation activity that most brassica species offer. By implementing a full renovation programme farmers benefit in both the short term and the longer term.
The table below shows the total dry matter yield of Goliath v Greenland for different trial sites and different trial years. The data shows that the two varieties produce very similar yields when grown in the same environment.
|11 Gundgai||11 Ballarat||12 Ballarat||12 Gundagai||13 Ballarat||14 Ballarat||Ave. Yield|
Goliath rape, like all forage brassica, is a small seed, so sowing depth and seed to soil contact are critical to the success of establishing a good crop. Sowing depth should be no greater than 10mm with good seed to soil contact to make sure that moisture gets to the seed.
Rolling after sowing or the use of press wheels are recommended as this will give a more even establishing crop of Goliath. Phosphorus is a critical macro nutrient that is needed for the early growth stages of any brassica crop. The best application is to have the fertiliser placed near the seed in the ground. Nitrogen is also an important nutrient at the time of sowing a brassica crop.
Be sure to have a soil test taken prior to sowing any brassica crop because it will indicate the status of not only the macro and micronutrients, but the soil condition and if any corrective measures need to be implemented.
Goliath is a ‘giant’ type rape and the maturity, as a general rule, is later than that of the intermediate types (Titan) which can be a challenge in some years when rainfall is limited in a dryland situation. However, unlike older varieties of forage rapes where the leaves/leaf margins are required to turn the characterised purple/bronze, Goliath’s leaves stay a green colour. Goliath rape should still be grazed at the required grazing period of 90-120 days after sowing to maximise animal performance and limit the possibility of animal health issues whilst grazing the crop.
Animals should never graze an immature rape crop because of potential animal health risks. New generations of forage rape bred by PGG Wrightson Seeds have all, regardless of its parentage, been bred with the grazing animals as part of the breeding programme. This is to ensure that the production benefits of both the Goliath forage rape crop and the grazing animal are achieved.
For maximum regrowth and highest potential yield, rotational grazing rather than set stocking is recommended. Another method is to strip graze the crop, but be sure to use a back fence so that the crop recovery and subsequent regrowth is not compromised. Avoid hard grazing at any stage as this can cause damage to the crown of the plant and therefore affect the potential for regrowth and overall yield.
Feeding a good quality fibre source to all ruminants can aid digestion when utilising high quality feed such as forage brassica. The purpose of the fibre is to encourage the animal to chew. The chewing encourages salivation and saliva is a rich source of sodium bicarbonate which acts as a buffer that helps balance the acids produced during fermentation in the gut. Fibre also helps with firming
up liquid dung that is often seen when animals are grazing high quality feed.