Grazing Management

The following basic feeding guidelines have been developed from many years of trialling and monitoring brassica crops, and are designed to help maximise the animal production from brassicas.

1. Don't allow stock sudden unrestricted access to a brassica crop.
Sudden access can upset the balance of rumen microbes, resulting in poor animal performance, scouring and acidosis. Start by grazing the crop for no more than two hours per day, building up to a maximum allowance over at least 7-10 days. Allow rumen microbes time to adjust to the high quality forage.

2. Feed extra fibre prior to and while grazing brassica crops.
Forage crops are highly digestible, and don't contain much 'effective fibre', the sort of fibre that makes animals chew.
Feeding extra effective fibre means:

• More chewing and increased salivation, which helps maintain rumen pH and as a result there will be fewer digestive upsets.
• Slower flow of feed through the rumen and gut, with a more effective rumen fermentation.
• Increased cud chewing and more effective digestion.

Extra fibre should be given prior to and throughout the brassica feeding period, through access to pasture, hay or straw. This will help to prevent gorging, help rumen microbes adjust to the feed and help to maintain normal rumen function. It is suggested that 30% of the diet is fed as hay, straw, or runoff pasture.
The following trial results show the effect of feeding a source of fibre with Pasja.

3. Feed brassicas as part of a balanced diet.
Animal performance on brassicas is best when crops are fed strategically as part of a balanced diet. For example, the high protein and energy of brassicas complements stalky summer ryegrasses which can be deficient in energy and protein, or whole-crop cereal and maize silage's which are low in protein.
Forage brassicas are high in energy and protein, but low in crude fibre. For this reason they will need to be rationed to balance the total feed requirements of your livestock.

• For dairy cows the total of grain and brassicas should not exceed pasture plus hay/silage. The economic level of feeding forage brassicas is usually about 5kg/cow per day.
• For sheep and beef cattle grazing for liveweight gain, stock should be introduced gradually increasing the ration over 5-7 days. They should always have access to a run off pasture paddock or hay/straw making up 15% of the diet.
• Utilisation can be increased from 65% up to 85% using electric fencing.

4. At all times give animals access to water when grazing a brassica crop.
Although the water content of brassicas is high, it is recommended that animals have access to fresh water at all times as a limited water intake will cause an animal's dry matter intake to decline.

5. Recognise potential for stock health problems
Feeding brassicas can sometimes be associated with animal health problems. Risk can often be avoided by good agronomic and grazing management.

• Animal health problems can occur when introducing stock to brassica crops or grazing under overcast conditions or after heavy rain.
• Photosensitisation can occur if crops are fed when still immature. You should wait for the correct maturity time before introducing animals.
• Ensure stock have access to adequate water
• Stock should be introduced slowly to forage brassicas over the first week to enable the rumen the time to adapt to the change of diet.
• Nitrate poisoning can occur under extreme conditions when overcast after heavy rain or during thunderstorms. It is advisable to keep stock off brassica crops until the weather clears.