The autumn stand of lucerne pictured is getting stalky as it starts to flower. With more stalk and flower, and less leaf, the protein intakes are not as high as they are when the plant is young.
At this stage, it is safer to graze animals on the pasture. In autumn, be aware of cooling nighttime temperatures, which can be a problem. Rather wait for the dew to burn off in the mornings.
Farmers call it the king of hay and there is nothing more beautiful than a shed filled with lucerne bales when a drought strikes. Lucerne is a legume that grows for longer than a season and fixes nitrogen in the soil. It is good for grazing or when baled as hay.
Take care, however: ruminants like sheep, cattle and goats can bloat on stands of young lucerne. While some animals, like Merinos, are less prone to bloat, the financial benefits of growing lucerne and grazing this productive legume with its good yields and high protein and mineral content make it worthwhile, even though it requires some management.
Bloat is when gas builds up an animal’s rumen. This happens especially when the lucerne plant is still growing (vegetative stage) – in other words, there’s more leaf than stalk.
Animals can easily eat it at this stage, as it doesn’t have much fibre, but it is the high protein content that causes the rumen to release gas, leading to bloat.
This type of bloat, caused by a high intake of grazed legumes (lucerne or clover), is called frothy bloat. The danger of bloat is highest during autumn and spring. Once the lucerne plant flowers (more stalk than leaf), the risk is greatly reduced. Keep in mind that lucerne does not cause prussic-acid poisoning.
HOW TO PREVENT BLOAT
■ Don’t let animals graze lush stands of young, fast-growing lucerne – wait until the lucerne flowers, then graze it.
■ Wait until any moisture from dew or rain has burnt off before you put the animals onto the pasture.
■ Never put hungry animals onto lucerne.
■ Plant a mix of lucerne and rye grass. The more diverse the pasture, the better. Plantain is said to have anti-bloat properties.
■ If you’re kraaling animals at night and they graze lucerne pastures during the day, make sure they get enough decent hay in the kraal so that they don’t go to the pasture hungry the next day.
■ Put good-quality hay in every camp.
■ Make the animals used to the lucerne by gradually increasing the time they spend on the pasture until they are used to it.
■ Ensure there is enough drinking water. Dairy farmers in the Eastern Cape manage bloat by putting sweet oil in drinking water.
■ Keep Bloat Guard (for cattle, sheep and goats) handy.
■ Check animals regularly, especially at high-risk times of the year. Bloat will kill if left untreated, but treated animals will recover fast.
WHEN TO GRAZE LUCERNE
Grazing immature lucerne increases the chances of bloat and shortens the life span of the lucerne. If you graze it hard in late summer and autumn, you should probably rest it the following spring and early summer.
Lucerne can take a lot of grazing, but it does need one good rest (40 to 50 days) in the season.
Remember, sheep and goats are selective grazers and may damage the pasture if they graze for a long time. Cattle are not as selective, but they can also affect the lifespan of the lucerne if they are allowed to graze it too short.