"WE EXPECTED to find a big variation in the percentage of hull between varieties and weren't surprised when we turned up a range of 16 through to 75 per cent, " said NSW Agriculture's animal nutrition expert, Alan Kaiser.
"What did surprise us was the variation in the digestibility of the hull. It ranged from 26 to 75 per cent, with the digestibility declining as the amount of lignin present increased. Moreover, there seems to be a correlation between the variation in digestibility and the breeding program that developed the variety.
"The samples at the lower end of the lignin and upper end of the digestibility measurements came from the dual-purpose breeding programs in NSW and Tasmania. The samples high in lignin and low in digestibility came from the specialist grain-breeding programs in WA and SA. "
The implications are significant. Tests carried out in the USA show that, at their best, oats as a feed grain are at least as good as, if not better than, corn. "It's slower to digest and poses less chance of grain poisoning but, when you get a variation in energy content within oat samples of 8-14 megajoules, it's no wonder that the grain has fallen out of favour as a component of feed rations, " says Dr Kaiser.
"Fortunately we've identified the major cause of the variation and can begin a breeding program to counter it. Glenn Roberts, the oat breeder with the NSW Department of Agriculture, has already tested most of his breeding lines and identified about 20 per cent that are low in lignin. "
Dr Kaiser and Peter Flinn, of the Department of Primary Industries, Sustainability and Environment in Victoria, have also developed an NIR test, which has proved to be accurate for measuring the digestibility of the whole oat grain.
"Total digestibility also seems to be highly heritable and breeders are planning to make use of this test when it becomes available in 2003. In time I would expect it to be picked up by the trade and used as a trading tool, " he says.