Description

Plant protein feedstuffs (PPF) may play an essential role in decreasing feed costs in aquaculture by reducing the use of fishmeal to minimal inclusion levels. Further supplementation may be needed to fulfill the fish's nutritional requirements. A feeding experiment was conducted to reduce fishmeal in practical diets of seabass juveniles reared in fresh water. The first diet was formulated to contain fishmeal as the only animal protein source. Four mixtures of rice gluten (R) soy protein concentrates (S) and corn gluten (C) in different formulations expressed as 10-0-21, 17-0-21, 0-10-21, and 0-17-21 RSC and named diets 2, 3, 4 and 5, respectively, were used to reduce fishmeal in the experimental diets from 20% to 14% (diets 2 and 4) or 7% (diets 3 and 5) of whole ingredients percentage. A reduction of fishmeal inclusion level in sea bass diets from 20% down to 14% had a positive effect by using PPF mixture of 10-0- 21 RSC. However, reducing dietary fishmeal to 7% gave a negative response in growth parameters, specific growth rate, protein efficiency and energy retention of juvenile seabass. Final body weight, weight gain, feed conversion ratio, protein and energy utilization efficiency were not significant (P>0.05) among fish fed the basal diet that had 20% and those fed 14% fishmeal diet, with a PPF mixture of 10-7-21 RSC. Feed intake of sea bass juveniles was significantly (P<0.05) low upon reducing fishmeal in the experimental diets. The Feed conversion ratio of fish-fed diets containing a high percentage of rice gluten was higher, compared to the control diet. Histological examination of individual villus showed several symptoms of sub-acute intestinal enteritis of fish fed rice gluten, several of which appeared fewer in fish fed soy protein concentrates. The present study concluded that dietary soy protein concentrate seems to be more suitable to reduce fishmeal in seabass diets than rice gluten at level 33% replacement. In addition, incidence cost and profit index were improved as fishmeal was replaced by PPF in the diets of sea bass.

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Brief

It may be possible to use different mixtures of plant protein sources to replace fishmeal in diet of sea bass juveniles rearing in fresh water. It showed no significant (P>0.05) effect on growth performance, nutrient utilization efficiencies, body composition and incidence cost in case of replacing of 33-66% fishmeal by plant protein feedstuff.

KeyWords

European seabass, Fishmeal reduction, Growth performance, Feed utilization, Plant protein feedstuffs, Incidence cost