UNAIR NEWS – The high price of animal feed raw materials makes vegetable fish meal an alternative to meet the feed needs in the aquaculture sector. However, its use still requires a lot of consideration because of the high amount of anti-nutritional substances contained in vegetable protein sources.
Pelletting is one way of making feed through compressing a mixture of materials with mechanical pressure. The weakness of the pelleting process is that the anti-nutritional substances in the feed are still left because they are only processed using mechanical pressure. Furthermore, the protein in feed is still in a complex form.
On the other hand, making pellets by means of extrusion has been proven to be able to maximize feed raw materials derived from vegetable protein. It was conveyed by Dr. Romi Novria in a guest lecture held by the Faculty of Fisheries and Marine Sciences (FPK) Universitas Airlangga.
The postgraduate lecturer at the Jakarta Fisheries Business Analysis Polytechnic (AUP) Ministry of Marine Affairs and Fisheries, Republic of Indonesia revealed that anti-nutritional substances such as phytic acid, saponins and lectins contained in soy flour or tannins, protease inhibitors and saponins found in nuts and seeds can affect the digestibility of feed. However, it can be anticipated by the extrusion process.
“Extrusion is a process of combining a working system of mixing, cooking, kneading, shearing, shaping, and forming using a tool called an extruder,” said Romi.
Romi continued, the working principle of the extruder is that the raw material inserted into the barrel will be pushed and stirred by a screw at a very high speed, the friction between the material and the barrel can create hot temperatures that can remove water content. The molecular density of the pellet is also high due to the pressure built up in the extruder machine.
“Due to the fast heating and stirring process in the extruder machine, the anti-nutritional substances in the ingredients can be removed, because apart from chemical processes, the anti-nutritional substances can be minimized by a physical process,” he said at a virtual guest lecture held on Thursday, April 28.
Apart from being able to remove anti-nutritional substances, the pallet extruder can also create pellets with longer form stability in water. He also explained that using an extruder we can make 2 types of pallets, sinking and floating which are difficult to do with a pelleter.
“This is also very important because in addition to the composition that must be balanced, the quality of the feed is also determined by its physical properties, pellets with low palatability even though they have high nutritional content will only cause waste in the cultivation medium,” said Romi. “Therefore, the stability of the form of feed in water is one of the considerations in selecting feed for cultivation,” he continued.
This has also been proven through several studies comparing the use of pellets from extrusion process and pelleting. In shrimp fed with extruder pellet feed, the weekly growth can reach 0.99 grams, while regular pellet feed is only 85 grams.
“In addition, the digestibility of nutrients from the extruder feed is higher because the physical process when carrying out the extraction can simplify complex molecules in the feed and remove anti-nutritional substances, this is evidenced by the higher digestibility of protein (DAP) extruder pellets than ordinary pellets,” explained Romi.
At the end, Romi said that even though it has several advantages, operating extruder pellets requires a large amount of capital. However, if you look at the long-term benefits, the use of an extruder can be considered.
“As the fee price continues to increase, the use of extruders may be an option to realize the Independent Fish Feed Movement program, so that cultivators can reduce the cost of procuring feed,” he concluded. (*)
Author: Ivan Syahrial Abidin
Editor: Nuri Hermawan
