Page 37 - New additives and ingredients in the formulation of aquafeeds

Traditional feed formulations for marine fish are high in marine ingredients,
containing 40-50% good quality fish meal and 10-15% fish oil. Animal by-
products, including specific qualities of poultry by-products and bloodmeals,
offer interesting alternatives in terms of nutritional profile and digestibility
but are not always an alternative to fish meal due to market conditions (eg
high demand by the petfeed industry) and/or consumer concerns. Increased
replacement of fish meal/fish oil by vegetable protein sources derived from
soybean, wheat, rice and corn offers possibilities to stabilize formulation
cost in marine fish feeds. However, many nutritionists are hesitant to use
high levels of vegetable protein in marine fish feed due to the fear for
slower growth and poorer feed conversion compared to traditional feeds
containing high levels of fish meal. Carnivorous fish – like any other animal
– require a balanced diet which is satisfying nutritional requirements and
of acceptable palatability/digestibility to promote ingestion/digestion.
Formulating marine fish feed with less marine ingredients requires good
knowledge of nutritional requirements and functional/nutritional additives
which are capable of solving some of the typical problems encountered in
carnivorous fish fed high levels of plant protein, such as reduced palatability
and digestibility, anti-nutritional factors and amino acid misbalances.
One of the challenges for replacing fish meal by vegetable protein sources
in feeds for carnivorous fish is the effect of vegetable ingredients on lipid
digestion, absorption and deposition. This has recently been documented
for a number of carnivorous fish species including atlantic salmon (Kroghdal
et al. 2003), rainbow trout (Romarhein et al., 2008) and gilthead seabream
(Gómez-Requeni et al., 2004). This presents an important challenge for
improving low fishmeal diets due to the importance of dietary fat in the
energy balance of marine fish.
The addition of a digestibility enhancer with main emphasis on lipid diges-
tion for carnivorous fish (AQUAGEST® CAF) to practical feed formulations con-
taining reduced levels of fishmeal improves significantly growth (with 6.5%),
food conversion ratio (with 7%) and protein efficiency ratio (PER, with 7.6%)
in a marine, carnivorous fish such as European seabass (Dicentrarchus labrax;
Improving
performance
of carnivorous
marine fish fed
low levels of
fishmeal
Figure 6. Data from a
84-days culture trial with
European seabass using
triplicate tanks of 600 L
per diet. Fish were grown
at 20-22°C in a seawater
recirculation unit from 224g
to ± 318g. The control diet
consisted of a practical
coated-extruded grow out
(crude protein 45%; crude
fat 20%), containing 19.6%
Peruvian fishmeal (67%CP);
17% fish oil, 5.9% wheat
gluten, 6% corn gluten, 5%
pea protein concentrate,
32% defatted soybean
meal, 8.5% wheat flour,
4% extracted rapeseed
meal, 1.15% monocalcium
phosphate, methionine
0.1%, lysine 0.2%, premix
0.55% (vitamins, minerals,
antioxidant, antimould)
(Coutteau et al., 2010)
Innovative approaches to reduce feed cost in aquaculture: optimizing nutrient utilization and gut health 35
Fig. 6. Data from a 84-days culture trial with European seabass using triplicate tanks of
600l per diet. Fish were grown at 20-22°C in a seawater recirculation unit from 224g to ±
318g. The control diet consisted of a practical coated-extruded grow out (crude protein
45 ; crude fat 20%), containing 19.6% Peruvian fishmeal (67%CP); 17% fish oil, 5.9%
wheat gluten, 6% corn gluten, 5% pea protein concentrate, 32% defatted soybean meal,
8.5% wheat flour, 4% extracted rapeseed meal, 1.15% monocalcium phosphate,
methionine 0.1%, lysine 0.2%, premix 0.55% (vitamins, minerals, antioxidant,
an imould) (Ceulemans et al., 2010).
IMPROVED FEED
CONVERSION
1.3
1.4
1.5
1.6
1.7
1.8
CONTROL AQUAGEST
CAF
-7%
IMPROVED GROWTH RATE
(%/day)
0.35
0.40
0.45
CONTROL AQUAGEST
CAF
+6.5%
IMPROVED PROTEIN
EFFICIENCY
1.10
1.15
1.20
1.25
1.30
1.35
1.40
CONTROL AQUAGEST
CAF
+7.6%