Grazing Pregnant and Lambing Ewes on Cereals

Andrew Thompson, University of Western Australia & David Masters, Murdoch University - Meat & Livestock Australia

Type: Research Paper
Knowledge level: Advanced

Farm Table says:

This specific aims of the project was to increase the productivity of pregnant and lactating ewes grazing winter cereals in mixed farming enterprises of Western Australia (WA).

Fail safe guides

What is the problem?

A combination of a literature review and surveys of producers and consultants was used to identify the benefits and risks of grazing young cereal crops with reproducing ewes.

What did the research involve?

Using a combination of census data and responses to web and phone surveys, it is estimated that the current cost of increased mortality in pregnant ewes resulting from grazing crops is approximately $15,700,000 pa. This is likely to be a significant underestimate of the benefits from providing fail safe grazing strategies.

What were the key findings?

  • Young growing crops have excellent nutritive value with high digestibility and protein levels that could be grazed to fill a winter feed gap where availability coincides with increased feed requirements in pregnancy and early lactation.
  • Maintenance or liveweight gain is possible at much lower food-on-offer levels than would be required for pastures. However, young growing crops contain an imbalance of potassium, sodium, magnesium and calcium that can cause metabolic disease (sodium deficiency, hypomagnesaemia or hypocalcaemia) and possible mortality in sheep.
  • Risks of metabolic disturbance are higher for sheep grazing wheat than other young cereals. Preliminary evidence indicates risks are higher when grazing cereal crops in NSW, Vic and SA than in WA.
  • Consultants and producers indicated there is uncertainty around the benefits of mineral supplements. Producers using recommended supplements have still reported metabolic disease and mortality. In some cases these supplements may even exacerbate the mineral imbalance problems in late pregnancy.
  • There is a lack of knowledge on how to manage sheep in large cropping paddocks and on the shelter benefits from lambing in crops.
  • Management of ewes grazing cereals in is largely by trial and error as there has been limited evaluation of different grazing strategies.
  • The interviews and surveys indicate that a significant numbers of producers avoid grazing young cereals with ewes in late pregnancy because of the apparent health risks. The risks were much more strongly expressed by producers in NSW, Vic and SA than those in WA. Further work will investigate management strategies.

 

Final comment

Cropping and livestock have always had synergies through the use of crop stubbles to provide feed for livestock in summer and the use of pasture phases to manage fertility, diseases and weeds in cropping paddocks.

 

2015 - Australia - Andrew Thompson, University of Western Australia & David Masters, Murdoch University - Meat & Livestock Australia
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