Lupins edging into AQUACULTURE

A net cast to collect prawn samples from a pond at cleveland, qld.

AQUACULTURE, the fastest-growing intensive livestock industry in the world, promises opportunities for highprotein crops like lupins and field peas.

The market for fish feed is projected to treble within ten years and demand is expected to outstrip supply of fishmeal, currently the critical component in all fish feeds.

Demand for fish feed is expected to grow from the present 1l.9 m tonnes to around 35 m tonnes by the end of the decade.

Already one-third of the world's supply of fishmeal is used by the industry and the supply is limited and varies with seasonal conditions. Other intensive industries like poultry, pigs and pet food are competitors and increasing demand is expected to drive up the price to a point where feeders will have to turn increasingly to vegetable protein sources.

Unlike land-based livestock, fish don't make use of carbohydrate for growth, relying instead on the protein and fat component of feed stuffs. Soymeal is currently the most commonly used vegetable protein source, contributing up to 15 per cent of some rations.

Working on a lupin for soy replacement

In a project backed by growers and the Federal Government through the GRDC, David Petterson, of the WA Department of Agriculture (Mr Petterson has since become a private consultant), demonstrated that dehulled lupin meal could be used as a replacement and, in fact, was slightly more digestible than soy meal. However, he agrees with CSIRO scientist David Smith that this is only part of the story. Mr Smith found that when he tried to replace most of the fishmeal in a prawn diet with dehulled lupin meal, growth rates decreased.

Mr Petterson speculates that this may have something to do with the non-starch polysaccharides in the grain, which have already proved a problem with poultry, or it could relate to its comparatively high fibre. His work is focused on finding the answers that could lead either to specific plant-breeding programs or processing techniques to overcome the problem. Southeast Asia, China and India are the big growth markets for aquaculture and Mr Petterson says that, on a straight comparison with soy meal, lupins should fetch a significant premium above their current market price. Mr Smith argues that the real need is for information that would convince feed compounders that lupins are an economical alternative to soymeal.

Less waste by-product

Lupins may have one significant advantage in what is an increasingly sophisticated market. Brent Glencross of Fisheries Western Australia has found that fish retain the phosphorus content of lupins more successfully than that from soymeal.

Factors such as the breakdown of feed pellets, undigested waste and nitrogen and phosphorus excretion are all recognised by the industry as serious problems.

Besides contributing to downstream environmental pollution, they can result in large microalgal blooms in ponds which, in the early hours of the morning, can reduce ayailable oxygen to dangerously low levels.

Mr Petterson believes this could give lupins an edge in the large Norwegian salmon industry where environmental concerns are already a high priority.

So fast is the growth in the industry that just two Chinese provinces could take the entire Australian lupin crop and we'd still not keep pace with the growing demand. Finding the answers to making the grain more acceptable to the industry should be well worth the effort.

Our own aquaculture industry, while tiny by comparison, is also growing rapidly. Mr Smith says that it could be "the test tank for developing grain that opens up the world market".

Program 5 Contact: Mr David Petterson 08 9386 6195, Mr David Smith 07 3826 7239 email david.m.smith@csiro.au