Good transition feeding starts with knowing your hay

With hay season underway across the Murray region, my advice to farmers is simple: make testing part of your plans for securing springer hay.

Whether you’re making your own hay or buying it in, knowing its mineral content helps you make informed decisions about your transition diet. The hay you choose now can play an important role in preparing cows for calving and their next lactation.

One useful measure is dietary cation-anion difference, or DCAD. While the name sounds technical, understanding what it means can help you select suitable hay and reduce the risk of milk fever.

DCAD describes the balance between four minerals in the diet. Potassium and sodium increase the DCAD value, while chloride and sulphur reduce it.

Before calving, a low DCAD diet helps cows mobilise calcium stored in their bones to meet the increased demand around calving. Dairy Australia recommends a total diet DCAD of around minus 50 milliequivalents per kilogram of dry matter in the last four weeks before calving.

Getting the other minerals right matters too. Recommended dietary targets are 0.4–0.6 per cent calcium, 0.4 per cent magnesium and 0.25–0.45 per cent phosphorus, expressed as a percentage of total diet dry matter. Together, these targets help minimise the risk of milk fever and prepare cows for lactation.

But you can’t tell whether hay is suitable just by looking at it.

A representative sample sent to an accredited feed laboratory will give you a clearer picture. Ask for wet chemistry testing for potassium, sodium, chloride and sulphur, and a calculated DCAD value, these are included in the standard Near Infrared Spectroscopy (NIR).

Cereal hays are often used for springers because they generally contain less potassium than pasture hays. However, mineral levels vary between hay sources and batches. Testing gives you the information you need to assess whether a particular hay will suit your transition program.

It’s also important to remember that the target applies to the total diet. Low DCAD hay is a useful starting point, but every feed in the ration contributes to the final balance.

Zeolites and Anionic salts, including magnesium chloride and magnesium sulphate, are often included in commercial lead feeds to help lower the total diet’s DCAD. A trusted nutrition adviser can help you interpret your results and balance the ration for your herd.

Dairy Australia’s Transition Diet Milk Fever Risk Calculator is another useful tool for assessing your diet once you have your feed test results.

For me, the key message is to plan early. A feed test is a practical step you can take now to help give your cows a strong start to their next lactation. Testing hay before committing to a purchase, or allocating your own hay to springers, gives you more time to make suitable choices. 

If you would like to better understand your transition program, register your interest in Dairy Australia’s Transition cow management workshop, planned for the Murray region in the new year. 

For further information and tools, visit transition managment resources.