August 26, 2002

Research into what¹s called "waxy" sorghum is to continue, after an industry workshop agreed that the trait is likely to bring significant benefits to the value chain ­ including the possibility that it might improve meat quality in feedlot cattle.

Grain endosperm in sorghum containing the "waxy" gene also appears to have potential to improve digestion in ruminants ­ important to the feedlot industry ­ and to reduce processing costs in milling and pelleting of stock feeds.

The ongoing research will be carried out under the Queensland Department of Primary Industries core breeding program, which recently won a new, five year round of support from graingrowers and the Federal Government through the Grains Research & Development Corporation (GRDC).

QDPI principal plant breeder and sorghum program leader Bob Henzell said private sector plant breeding and the intensive livestock, feed milling and grain handling industry sectors were all represented at the workshop that agreed on the potential value of ongoing waxy sorghum research.

"One of the real strengths of sorghum research in Australia is the high level of collaboration amongst the scientists from different disciplines, from different institutions and with the wider industry," Dr Henzell said.

"The QDPI breeding project ­ as well as the private sector ones carried out by Pacific Seeds and Pioneer Hi-Bred ­ are a significant vehicle for the enhancement of many sorghum research projects, including the ones supported by the GRDC.

"Research at the University of New England, under the GRDC¹s Premium Grains for Livestock Project, identified the potential of waxy sorghum to improve meat quality.

"That theory is based on evidence that the ratio of starch digested in the small intestine, to that fermented in the rumen, is higher in waxy than in non-waxy sorghum.

"The significance for meat quality is that the glucose from starch digested in the small intestine produces a fat that is better distributed in the meat than that from starch produced from fermentation in the rumen, a greater proportion of which ends up in subcutaneous fat."

Dr Henzell said other indications from to-date research into waxy sorghum were:

o when "dry-rolled" for cattle ­ the process generally used by all but the biggest feedlots ­ waxy sorghum delivered between $10 and $15 more nutritional value a tonne than non-waxy sorghum; that¹s much the same margin as the currently preferred barley has over non-waxy sorghum;

o potential transport savings, because much stockfeed barley was brought from southern states, whereas any new production of waxy sorghum would come from northern NSW/Queensland;

o with a lower gelatinisation temperature and better hydration, waxy sorghum had potential to reduce problems of crumbling and slower throughput now experienced with non-waxy sorghums in the production of pelleted stock feeds; nutritionally sorghum was the preferred grain for poultry and was a
good grain for pigs but, because of poor durability, use of sorghum was restricted to about 55 per cent in pig and poultry diets.

Dr Henzell said there was a question about the yield of waxy sorghums, with considerable evidence that, currently, it was significantly lower than that of the commercial hybrids.

However, that had been the situation not that long ago in maize in the United States, where currently available waxy hybrids were now achieving yields comparable to non-waxy ones. .

Lower, early yields were most likely due to less breeding commitment to waxy lines. Because there are no apparent physiological or biochemical reasons for waxy sorghums to be lower yielding, marker assisted backcrossing of the waxy gene into the best hybrid, commercial parents should produce high
yielding, waxy hybrids."