Wheat grains fermented by fungal mycelia (Pleurotus ostreatus or Lentinus edodes) as alternative feed ingredients for juvenile rainbow trout (Oncorhynchus mykiss)

PASCUAL, MARIANO M.; HUALDE, JUAN P.; BIANCHI, VIRGINIA A.; MORENO, PABLO; CASTRO, JUAN M.; LUQUET, CARLOS M.

AQUACULTURE INTERNATIONAL

SPRINGER

Lugar: Berlin; Año: 2018

0967-6120

We investigated the effects of replacing non-fermented wheat grains with wheat grainsfermented by fungal mycelia in the diet of juvenile rainbow trout (Oncorhynchus mykiss).We assessed growth performance, feeding parameters, and body composition in three exper-imental groups (0.33 ± 0.01 g, in triplicates of 50 individuals each). The diets for all the groupscontained ca. 43% protein and 19% lipids. Experimental diets were made by replacing the100 g kg−1of wheat grains present in the basal diet (CTRL) with the same proportion of wheatgrains fermented by Pleurotus ostreatus (PWD) or Lentinus edodes (LWD) mycelium. Fishwere fed to apparent satiation twice a day for 56 days. Both, PWD and LWD, significantlyincreased fish body weight from day 28 onwards. Final body weight was 2.37 ± 0.04 g(CTRL), 4.29 ± 0.02 g (PWD), and 3.50 ± 0.05 g (LWD), and feeding efficiency (%) wasincreased from 64.5 ± 0.7 (CTRL) to 92.5 ± 0.5 (PWD) and 84.8 ± 1.5 (LWD). The experi-mental diets also improved nutrient retention efficiency (%): 30.0 ± 0.5 (PWD), 27.7 ± 1.1(LWD), and 21.0 ± 0.1 (CTRL), for crude protein; 40.3 ± 0.6 (PWD), 31.0 ± 1.8 (LWD), and16.1 ± 0.7 (CTRL), for ether extract; and 16.1 ± 0.1 (PWD), 14.0 ± 0.3 (LWD), and 11.6 ± 0.6(CTRL), for phosphorus. Body lipid content was highest for PWD followed by LWD andCTRL (81.4 ± 1.4, 63.2 ± 2.5, 42.3 ± 2.6 g kg−1, respectively), while viscerosomatic index waslowest for PWD (p < 0.05). Liver glycogen in LWD and PWD fish (0.62 ± 0.10 and 0.21 ±0.08% liver weight) was significantly higher than in CTRL fish (0.05 ± 0.01% liver weight).Wheat-mycelium meals appear to be suitable dietary ingredients for improving juvenilerainbow trout growth and nutritional performance. These benefits vary according to themushroom species used.