Complete Replacement of Fish Meal with Potential Aquafeed Ingredients for Rainbow Trout in Iran
Hamed Salehi, Stefan Reiser, Ulfert Focken
Thuenen Institute, Fisheries Ecology Branch Bremerhaven, Germany
Iran as the largest producer of rainbow trout in the world needs sustainable aquafeed resources to fulfil the needs of this growing industry. Therefore, the potential feed ingredients were evaluated in fish feeding trials for their suitability and use in aquafeeds before introducing them into the market. The fish growth performance and apparent digestibility coefficients (ADCs) of nutrients were investigated for three fish meal free diets in comparison to a commercial diet and a casein-based semi-synthetic laboratory standard diet. Formulated diets were designed to meet the nutrient requirements of rainbow trout and have protein and lipid contents equal to commercial diet. TiO2 was included as an indigestible marker to measure the digestibility of experimental diets. Two-hundred-fifty-two juvenile rainbow trouts with an initial average weight of 30 ± 3 g were stocked randomly in 18 experimental 57-l rectangular glass aquaria for 72 days. The diets were allocated to the aquaria in three replicates in a random-block-design. Feces were collected via settling method for four weeks at the end of the experiment. The results showed daily instantaneous growth rate, weight gain, feed intake and feed conversion ratio did not differ significantly among the diets. The plant-and-animal-based diet had similar protein efficiency ratio (PER) and nitrogen productive value (NPV) to commercial and laboratory standard diets. Apparent digestibility coefficients for crude protein were considerably differeent only between pure casein-based diet and plant-and-animal-based diet with the values of 98.7 ± 0.04% and 90.7 ± 0.29%, respectively. Our observations indicated that an acceptable performance could be achieved by applying poultry slaughterhouse by-products, canola meal and crystalline amino acids in carnivorous fish species without any fish meal and this may help to protect our planetary resources such as demersal fish stocks in seas.
Keywords: Aquaculture feeds, Iran, plant proteins, rainbow trout, rendered animal products
Contact Address: Hamed Salehi, Thuenen Institute, Fisheries Ecology Branch Bremerhaven, Herwigstr. 31, 27572 Bremerhaven, Germany, e-mail: hamed.salehithuenen.de