Mexico: A group of researchers from the Technological Institute of Tuxtepec (Ittux), in collaboration with colleagues from other scientific bodies, has developed aquaculture feed from bean residue in an attempt to reduce rainbow trout (Oncorhynchus mykiss) production costs.
The objective of the research, which involved researchers from the University of Hermosillo; Juárez University of Durango State and that of Nuevo Mexico as well as scientists from Durango Technological Institute, is to use the raw material in the region to generate low-cost feed that does not affect the quality of the trout.
Bean chaff (broken or chipped) represents a loss of 5 per cent of total annual production, so the decision has been taken to use this waste for the production of aquaculture feed for trout, explains Dr. Jesus Rodriguez Miranda, leader of this research, according to Conacyt Informative Agency.
The study was conducted in the state of Durango, a region ranking second in bean national production, considering information from the Secretariat of Agriculture, Livestock, Rural Development, Fisheries and Food (SAGARPA).
Farmed rainbow trout is usually fed with fishmeal but the high cost of this product represents 40 per cent of total production costs.
Dr. Rodriguez specifies that the final product contains a balanced diet with wheat flour, milk whey oil, fishmeal and bean flour, which replaced half the proportion of fishmeal. And he stresses that with this new feed it is possible to reduce rainbow trout feeding costs by 20 per cent.
The product was made by extruding feed, where flour and meals are processed through a screw, in short periods and with different temperatures, allowing the matter to be cooked.
"Feed must have adequate extrusion physical features to be consumed by the fish. The trout is a carnivorous fish that does not eat from the bead, so a slow sinking feed was developed, apart from being attractive and three times smaller than the animal's mouth," says the researcher.
As part of the study, rainbow trout from a farm were fed for 30 days with portions of 2.2 per cent of the fish biomass. At the end of the trial period, the researchers observed normal growth and weight of the fish, so they determined that the bean flour substitution does not affect the trout’s size and weight.
Dr. Rodriguez is now working on another project aimed at tilapia (Oreochromis niloticus), also with the aim of exploiting raw material in the region to help reduce production costs and thus benefit aquaculture producers.