Page 39 - New additives and ingredients in the formulation of aquafeeds

fromwhere it is transported to the target organs via the haemolymphe under
the form of lipoproteins. The formation and absorption of lipid micelles from
the lumen of the hepatopancreas tubuli is therefore a limiting step in the
lipid digestive process. Digestibility enhancers based on natural emulsifying
agents, selected for their compatibility with the shrimp’s digestive system,
have shown to be capable of complementing the process of emulsification
and absorption of dietary fats in the hepatopancreas. This in turn improves
the efficiency of shrimp to use fats as essential components and as source
of energy for growth.
Coutteau et al. (2011) reported on the use of a digestibility enhancer based
on natural emulsifiers to reduce the need for cholesterol supplementation
in the diet of tiger shrimp (Penaeus monodon). Experimental diets were
prepared by lab scale pelletizing. Diets were formulated to satisfy nutritional
requirements of P. monodon, except for cholesterol. Three feed formulations
were compared:
1) A control diet (CONTROL-) with no cholesterol supplementation and a
background concentration of 0.10% cholesterol (provided by the marine
ingredients fishmeal and shrimp head meal).
2) A positive control diet (CONTROL+) supplementedwith 0.15%cholesterol
to a total level of 0.25% cholesterol in the diet.
3) A test diet (AQUAGEST S) supplemented with a digestibility enhancer
based on an optimized blend of natural emulsifiers (Aquagest® S,
Nutriad International, Belgium).
Overall shrimp growth (up to 1.4 g/week) and survival (close to 90%), was
excellent under the conditions of clear water culture. Growth and feed
conversion were significantly improved by the supplementation of 0.15%
cholesterol. After 70 days of culture, harvested biomass was 33% higher
for the shrimp fed the diet supplemented with cholesterol (Table 3). The
digestibility enhancer was equally effective as purified cholesterol in
improving growth and feed conversion compared to the negative control
diet. After 70 days of culture, harvested biomass was 30% higher in the
AQUAGEST S treatment compared to the negative control.
Table 3: Survival, growth and food conversion of P. monodon fed during 70
days on different experimental feeds
Control
(0.1% cholesterol)
Control
(0.25% cholesterol)
Control
(0.1% cholesterol+
Aquagest)
Survival rate (%) 88.3±5.8 90.3±5.0 91.7±7.6
Initial Weight (g) 0.65±0.04 0.64±0.02 0.66±0.02
Final Weight (g) 5.9±0.4 a 7.8±0.4 b 7.5±0.2 b
Final Total Biomas (g) 103±2 a 137±9 b 134±8 b
FCR 3.9±0.2 a 3.1±0.2 b 3.4±0.1 b
Average ± SD from triplicate tanks; different letters in the same row denote significant differences p<0.05;
Coutteau et al., 2011
Innovative approaches to reduce feed cost in aquaculture: optimizing nutrient utilization and gut health 37