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Researchers Create Trout Feed From Bean Residue

Lucy Towers
10 January 2017, at 12:00am

MEXICO - In order to reduce costs in rainbow trout ( Oncorhynchus mykiss ) production, researchers from the Technological Institute of Tuxtepec (Ittux) have developed an aquaculture feed from the residues of beans.

According to Dr Jesús Rodríguez Miranda, leader of this research, the objective is to take advantage of the raw materials present in the region to generate low-cost food that does not affect the quality of the trout.

According to data provided by Dr Jesús Rodríguez, bean pellets (broken or husked) represent a loss of five per cent of the total annual production, which is why they decided to use this residue for the production of a trout feed.

The study was carried out in the state of Durango, which is the second largest producer of beans in the country, according to information from the Ministry of Agriculture, Livestock, Rural Development, Fisheries and Food (SAGARPA).

"The idea starts from the need for producers to reduce production costs, so an economic raw material was used that does not affect the growth of rainbow trout. Much of the fishmeal was replaced with bean flour, without impacting the growth of the product," Dr Jesus Rodríguez said.

Low-cost, high-performance food

The final product contains a balance of wheat flour, whey oil, fishmeal, and bean flour, which replaced half the proportion of fishmeal.

With this process, the cost of feeding rainbow trout decreased by 20 per cent. 

"The food should have the proper physical characteristics of extrusion to be consumed by the fish. Trout is a carnivorous fish that does not eat from the bottom, so the food has been designed to sink slowly. It has also been made attractive to the fish and three times smaller than the animal's mouth."

Dr Rodríguez explained that they underwent a 30-day feeding test on a farm. At the end of the test period, they noticed growth and normal weight of the fish, therefore they determined that the substitution for bean flour did not affect the size and weight of the trout.