Three tips for grazing winter cereal crops

PRODUCTION ADVICE - MAY 2020 - ANIMAL HEALTH

By Eve Hall
District Veterinarian
P: 0439 078 989 | E: eve.hall@lls.nsw.gov.au

Forage cereals – there’s no doubt they play a valuable and important role in a lot of grazing enterprises across southern Australia. They provide an opportunity to overcome the winter feed gap, have high winter growth rates, and a high carrying capacity, which allows us to ease the grazing pressure on pasture paddocks. We’ll almost certainly be seeing plenty of stock going out onto these crops in the coming months. So, what can you do to help get the most out of your stock on forage cereals this winter?

Minerals

Calcium and magnesium are the big ones here. Cereal crops are notoriously low in both. Pregnant, lactating and growing stock all have higher requirements for calcium and magnesium, so they’re at most risk of deficiency. To make things worse, cereals are high in potassium, which can inhibit the animal’s uptake of calcium and magnesium. If stock are low in calcium or magnesium, they may go down and even die due to hypocalcaemia or grass tetany.

Fortunately, supplementing stock with calcium and magnesium is pretty cheap and easy. Home-made loose licks are effective and affordable. Try mixing coarse salt, agricultural lime and causmag at a 2:2:1 ratio and have on offer in the paddock ad-lib. Beware, causmag has a bitter taste, so sometimes it helps to slowly introduce it to the mix over a week or so allowing stock to get accustomed to it.

Vaccines

Cereal crops are high in water-soluble carbohydrates, and this puts stock at an increased risk of an overgrowth of clostridial bacteria in the gut resulting in pulpy kidney and sudden death.

A booster vaccine (for example ‘5-in-1’) a couple of weeks before going out onto a crop is highly advisable. It’s a cheap, simple, and effective measure to reduce pulpy kidney losses during the change in diet.

Poisonings

Nitrate poisoning catches a few out every year. Nitrates are found in lush green feeds, especially those with a history of nitrogen fertiliser application. Keep in mind, high nitrates don’t always necessarily equate to poisoning; in fact, ruminants have the unique ability to convert nitrates into nitrite and then into ammonia, which can actually be used by the rumen.

The problems tend to arise when nitrate levels in the diet are suddenly at such high levels that the stock cannot convert the nitrate quickly enough. The result is a toxic build-up in the bloodstream that can cause some spectacular stock losses. The classic example is hungry stock that have been held in the yards for a day or two before being let out onto a lush green paddock where they ravenously eat and overload on nitrates.

Never suddenly introduce hungry stock to lush green feed – fill them up on hay first and shift them on later in the day rather than the morning.

To chat more about livestock health and grazing cereals, get in touch with your local District Vet or Livestock Officer by contacting your nearest Local Land Services office.