By Kellie Penfold
The recent drought has not only highlighted the nutritional value of often-ignored sheep food sources, such as stubble straw, it has illuminated the lack of research into supplementary feeding of livestock.
One of Australia"s only ruminant nutrition consultants, San Jolly, who runs Productive Nutrition in South Australia, says that very little research has been done on sheep nutrition and the role that crop stubble could play.
"Producers found over the drought, through improved nutrition with supplementary feeding, they were getting results such as increased lambing percentages," she says.
"They are now more confident about feeding their sheep, and are interested in feedlotting, but can"t find the nutritional information they need. Many have tried in the past and failed because they didn"t have the data on stocking rates and rations which would have got the results."
Ms Jolly says that as livestock producers have taken on the message that they need to increase stocking rates, they are now running fully stocked enterprises and are looking to nutrition to increase returns.
The other area Ms Jolly has identified as needing further research is the economics of stubble retention.
"We need to assess what are the viable options. Do you put sheep or cattle on it over summer with supplementary feeding, or do you bale it up and sell it to the feedlots? Where do you break even?
"It"s a saleable commodity and we need to look at the value of exporting the nutrients off farm."
Ms Jolly says the market for straw in sheep and cattle diets and the perceived dollar value of that straw will, in most years, relate to the supply of cereal hay, followed by the supply of rejected export hay.
She feels this market differentiation is generally unwarranted as in drier years the nutritive value of straw can be equal to or better than cereal hay.
"The dollar value of a balanced diet, in terms of increased milk production, increased lamb survival and a healthier rumen has not been measured in economic terms, however it is relatively simple to measure the direct benefit of baling and selling the stubble as straw," she says.
Straw - especially straw that is baled after being turned into chaff by the harvester - is a valuable fibre for ruminants because it:
Straw has become an important part of the ration formulation for high-producing dairy cows and it has a role in the diet of lot-fed cattle in total mixed ration systems.
"Also, combined with the increased role of straw in ruminant diets, vineyards have now entered the market, using straw as mulch under vines," Ms Jolly points out.
"But we have to weigh up that economic value with the fact the highest current Lambplan ram lamb growth rates are just under 600 grams per day and the current average growth rate of lambs is 250 grams per day. Keep in mind the 350 grams of potentially lost opportunity which is occurring around Australia.
"The other consideration is the estimated 11 million lambs lost at birth each year and the potential contribution of nutrition to that loss."
Ms Jolly says there needs to be more research not only on nutrition, but the effect of stocking rates on weight gains and realisation of genetic potential.
Source: Cottel, D (1991) Australian Sheep and Wool Handbook
Source: NRC (1985, 1987 & 2001) Nutrient Requirements of Sheep, Beef Cattle and Dairy Cattle
For more information: San Jolly, 0418 446499, firstname.lastname@example.org
Listen also: Harvest Radio - Stubble: Keep it or burn it?
CSIRO soil scientist Clive Kirkby explains how to decide which stubble management regime is right for you.