Salt with your lamb

Graziers filling the winter feed gap by growing winter wheat might find it worthwhile to provide stock with a little salt with their tucker.

Dual-purpose winter wheat is a useful option for farmers in Australia's high-rainfall zone as it can be grazed through mid-winter and recover to produce good yields of grain.

Recent research by Dr Hugh Dove in Canberra has shown that winter wheat, despite having a high nutritive value, often has low levels of magnesium and sodium and high levels of potassium.

Responding to studies that showed mixed animal responses to winter wheat, Dr Dove ran feeding trials which showed that supplementing feed with either magnesium or sodium improved liveweight gains by up to 25 per cent.

While it is difficult to tell if these are separate responses or an interaction, Dr Dove believes that the ratio of potassium/sodium in the rumen may be the critical factor, with increased levels of sodium improving magnesium absorption and therefore liveweight gains. The response to salt may therefore be a de facto magnesium response.

In practical terms, Dr Dove's research has shown that a simple salt:Causmag supplement, costing about one cent per sheep per day, can yield over 15 cents per day in liveweight gains.

Dr Dove describes the supplement as cheap insurance against lower than average liveweight gains, as well as a useful supplement for preventing grass tetany.

Future research will develop indicators to identify which winter cereals will benefit from mineral supplements.

Reference: Liveweight gain responses to magnesium or sodium supplements in young sheep grazing dual-purpose wheats, 2007. H Dove, G McMullen and WM Kelman. Journal of Animal and Feed Science, in press.

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