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« past issue’s references on lecithin and lupins

Dear Editor,

The section “Experts Answer” is surely an enrichment of your magazine. However, the answers on “Lecithin Application” (Vol. 1, No. 2, p.26) are unfortunately confusing to some extent. Heating fluid, viscose lecithin with fish oil requires additional work and creates extra cost. It is better to recommend the use of fluid lecithin of low viscosity which does not require heating and mixing with oil. Certain lecithin processors supply fluid lecithin with standardized viscosity according to customers demand. The recommendation to melt powder (de-oiled) lecithin and mix it with fish oil should not be given. This does not make sense and is uneconomic.

It might be helpful to readers of the magazine to mention the lecithin qualities available in the market:

• Crude lecithin (fluid) (unspecified phospholipid content);
• Standard lecithin (fluid) (fixed phospholipid content);
• Modified lecithin (fluid) (fixed phospholipid content; enzymatically or chemically modified); and
• De-oiled lecithin (powder) (90 – 92% phospholipids).

The article on lupins in your magazine (Vol. 1, No. 2, p. 11) was interesting. Australian lupins actually are the only which can be used in non-ruminants nutrition because of its negligible content of anti-nutritional factors. However, economically lupins are expensive relative to its nutritional value. This applies particularly to the de-hulled material. In this context it is regrettable that Table 1 does not provide information on the crude fiber content. Crude fiber is an important factor for evaluating the feeding value of a feedstuff. Another aspect that should have been covered in the article is growth data from the various feeding trials. The general statement on the performances of the animals fed with lupins is not very helpful. Whether lupins are useful feedstuff in aquaculture nutrition can be made, only if facts and figures are available.

Dr. Joachim W. Hertrampf

Authors respond to Dr. Hertrampf’s comments

Dr. Craig Russet on lecithin

I chose to give the feed manufacturer options on what "they" can do on site to reduce viscosity before telling them to "buy" a different lecithin. The company selling lecithin can make various adjustments to the lecithin to reduce the viscosity. These may include mixing various things with the lecithin (e.g. oils or fatty acids) or enzymatically or chemically modifying the lecithin. However, such adjustments have a cost. Feed manufactures should consider the total cost of viscosity reduction and decide whether they buy low cost, standard fluid lecithin and work around the viscosity problem or buy a modified lecithin that meets their application without any further effort.

The response on dissolving dry lecithin in oil was an answer to a “what if” question. My answer clearly does not recommend dissolving dry lecithin in fish oil or any other oil.

Dr. Brett Glencross on lupins

Literature values indicate that crude fiber levels of lupins vary widely from 25 - 250 g/kg. We have not analyzed crude fiber levels in the past and are looking into the aspect. I believe that the paper has provided plenty of data (nutrient composition data, digestibility data, maximum levels of inclusion determined from experiments) to determine the nutrient value of lupins. Page 14 provides a background summary of growth performance studies. The URL of the original report which contains such detailed information on the studies has been provided in the article. The data related to performance are also available in Aquaculture 235: 411-422. Finally, we have done studies comparing lupin kernel meals and concentrates with soybean meal and soy protein concentrates. These show that when diets are formulated on an equivalent DE and digestible protein basis, their performances are equal. Under practical formulation, a 38- 40% protein lupin meal fits into most salmonid formulations at around 8%-15%, depending on the cost and quality of competitor meals. Currently there are several major feed companies now using lupin kernel meals in their formulations and their main concern is understanding variability within the ingredient. Accordingly we spend most of our current efforts on understanding the limitations and constraints to using lupin products and their inherent variability and how best to manage it.