Dr Hugh Dove, CSIRO plant industry chief research scientist says further increases in profitability can be achieved by including a spring brassica phase between the pasture and cereal phases.

“In sheep grazing systems, cereal grazing can start when the available crop mass exceeds one to 1.5 tonnes of dry matter a hectare, provided the growing tip hasn’t advanced beyond 10 to 15 millimetres above the plant crown,” Dr Dove said.

“The amount and digestibility of wheat forage when grazing begins shouldn’t limit forage intake or liveweight gain by livestock.”

Dr Dove says supplementing young grazing livestock with magnesium and sodium would be “cheap insurance” because of the high potassium, very low sodium and marginal magnesium of wheat forage compared with animal requirements for growth.

He says growers who aim to get 1000 sheep grazing days from the crop are likely to have minimal impacts on grain yield.

“An example would be 33 sheep/ha for 30 days but higher stocking rates could be used provided the grazing period was shortened correspondingly.”

Post-grazi ng plant growth and development is slower than in ungrazed crops, so key stages such as flowering may be delayed by up to two weeks.

“This may be a useful effect, in terms of avoiding late frosts at flowering, but could also shift grain ripening into a hotter stage of the year and perhaps reduce yield,” Dr Dove said.

“In general, the effects of crop grazing on subsequent grain yield were small and when stocking rates were 35 sheep/ha or below, but became economically significant at stocking rates of 40-50/ha.”

Dr Dove says computer simulation studies show over 30 years at three sites whole-farm gross margins would be increased by 20pc by including dual-purpose cereal, with only a small and acceptable increase in the variability of farm income.