Replacing the substitute — Guar meal as an alternative for non-genetically modified soybean meal in the nutrition of rainbow trout (Oncorhynchus mykiss, Walbaum, 1792)

Autor: Pach, F., Nagel, F.
In:

Aquaculture nutrition

ISBN: 1365-2095
DOI: 10.1111/anu.12557
Seite: 666 - 672
Jahr: 2017

Einordung:
Institut: Professur Aquakultur und Sea-Ranching

Abstract:
Soybean meal (SBM) is widely used in aqua feed products. In the European Union, only
non-genetically
modified (non-GM)
SBM is accepted. However, global production of
non-GM
soybeans is declining and is limiting its utilization in aqua feeds. Therefore,
non-GM
SBM alternatives are required. In this study, guar meal was evaluated as a
substitute for non-GM
SBM in test feeds for rainbow trout (Oncorhynchus mykiss). Fish
(initial weight of 57 ± 10.1 g) were stocked to 12 experimental tanks of a freshwater
recirculation system with a stocking density of 6 kg/tank (500 L). Fish were organized
in triplicate groups and received isonitrogenous and isocaloric experimental feeds designated
as control and test feeds 1–3, where 0, 50, 100 and 150 g/kg feed of non-GM
SBM was replaced by guar meal. During the experimental test period of 56 days, fish
were fed twice a day until apparent satiation. Compared to the control group, daily
feed intake of test feeds 1–3 was significantly increased by guar meal inclusion. No
significant differences in feed conversion ratio and specific growth rate were detected
among all the treatments. Furthermore, guar meal inclusion did not affect protein efficiency
ratio. However, protein productive value was significantly impaired when guar
meal incorporation was above 100 g/kg feed. In accordance with the affected protein
productive value, the crude protein content of the proximate whole fish body declined
significantly. In contrast, condition factor, hepatosomatic index, slaughter yield and
fillet yield provided no significant differences between the experimental groups. In
conclusion, this study demonstrated that non-GM
SBM could be entirely replaced by
guar meal without affecting the general performance of fish and suggests guar meal as
an appropriate alternative for non-GM
SBM in the nutrition of rainbow trout.

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