Page 33 - New additives and ingredients in the formulation of aquafeeds

Data show results for growth (SGR, %/day) and feed conversion ratio
(FCR) relative to the performance of the non-supplemented control group.
Feeding trials were run in triplicate tanks for rainbow trout (trial duration 64
days; starting from 19 g); Nile tilapia (56 days; starting from 9 g); Pangasius
catfish (70 days starting from 16 g); and European seabass (84 days; starting
from 224 g) (Nutriad, internal reports).
Dose-reponse
trial for a
digestibility
enhancer with
Tilapia under
laboratory
conditions
Dose-response trials under lab conditions provide useful data to explore the
most cost-efficient dosage to be recommended for field verification. The
supplementation of 1.5 kg per MT of feed of a digestive aid (AQUAGEST®
OMF) yielded significantly better FCR (-5%), growth (+4%) and protein
efficiency ratio (+4%; Table 1). When increasing the supplementation from
1.5 kg to 3 kg per MT of feed, all these factors were further improved.
The hepatosomatic index was reduced by increasing the level of the feed
additive, amounting to a reduction of 11% for the 3 kg/MT supplemented
diet. The viscerasomatic index was reduced by 8% in the 1.5 kg/MT
supplemented diet. The decreased viscerasomatic and hepatosomatic
indexes and increased protein efficiency ratio indicate that more dietary
energy/protein is made available for growth. This allows the farmer to
improve feed conversion, fillet yield and reducing visceral wastes.
Table 1: Dose-response effect for a digestive aid in Nile tilapia (trial duration:
8 weeks; average (n=3) ± SD, different letters in the same row denote
significant differences at p≤0.05; Ceulemans et al., 2009)
Control aquagest®omf
1,5 kg/MT feed
% vs
control
aquagest®omf
1,5 kg/MT feed
% of
control
Survival (%) 100 ± 0 100 ± 0 100 ± 0
Initial weight (g) 9.17 ± 0.04 9.15 ± 0.13 8.93 ± 0.21
Final weight (g) 41.84 ± 0.83 44.32 ± 1.25 44.3 ± 1,99
SGR (% day) 2.71 ± 0.03ª 2.82 ± 0.03ab +4.1% 2.86 ± 0.08b +5.5%
Feed Intake
(g/ind) 37.86 ± 0.65 38.83 ± 1.18 38.3 ± 1.15
Feed Conversion Ratio 1.16 ± 0.01ª 1.10 ± 0.01b -5.2% 1.08 ± 0.03b -6.9%
Protein Efficiency Ratio 2.75 ± 0.03ª 2.86 ± 0.02ab +4.0% 2.92 ± 0.1b +6.2%
Hepatosomatic Index (%) 1.60 ± 0.15 1.48 ± 0.11 -7.5% 1.43 ± 0.01 -10.6%
Viscerasomatic Index (%) 8.45 ± 0.09a 7.79 ± 0.11b -7.8% 8.41 ± 0.13a -0.5%
Optimizing the
application strategy
for a digestibility
enhancer with
Tilapia under field
conditions
Sampaio-Gonçalves et al. (2012) recently evaluated different application
dosages of a digestibility enhancer as well as the effect of the basal feed
quality on the cost efficiency during a production cycle of Nile tilapia farmed
in cages in Brazil. The study evaluated the entire production cycle of tilapia,
including the processing of commercial size fish, and was carried out by the
Instituto de Pesca in collaboration with a commercial tilapia integration in
the Sao Paulo region, Brazil.
Innovative approaches to reduce feed cost in aquaculture: optimizing nutrient utilization and gut health 31