Page 42 - New additives and ingredients in the formulation of aquafeeds

The fillet ratio is an important criterion for the processor in the Pangasius
industry as the main market is sales of fillet. The fillet ratio was determined
in the fish processing plant of Hung Vuong Joint stock company after
harvesting the ponds.
Pangasius fillets are obtained in three stages, first the total fillet is cut
from the fish, secondly the skin is removed from the fillet, and finally the
fillet is adjusted to the market demands (less or more fat left depending
on the destination country. The first stage “whole fillet” ratio averages 1.9-
2.2 in Vietnam and is reported for the trials in Table 6. Overall, the whole
fillet yields obtained in the current trials were excellent in comparison to
the industrial average in Vietnam (1.9-2.2). Nevertheless, whole fillet yield
improved drastically in all trials because of the addition of the digestibility
enhancer, i.e. 2.4 to 4.6% for the lowest application and 7.4-7.5% for the
highest dosage evaluated.
Table 6. Effect of two different application regimes of a digestive aid on fillet
ratio (kg whole fish needed for 1 kg of whole fish fillet) of Pangasius catfish in
two trial locations in Vietnam (percentage shows difference compared to non-
supplemented control) (van Halteren et al., 2009)
Treatements
(see Table 4) TRIAL SITE 1: Tra VInh trial site 2: Sa Dec
Control 2.14 2.16
Aquagest 1 2.09 (-2.4%) 2.06 (-4.6%)
Aquagest 2 1.98 (-7.5%) 2.00 (-7.4%)
Growth
promotion
based on
optimized
gut health
and intestinal
microflora
The ban on the use of antibiotic growth promoters in poultry and pigs,
and the subsequent search for alternatives, has revealed the importance
of gut health and the development of a stable, favorable gut microflora,
on feed efficiency, overall performance and productivity. Fish and shrimp
are highly exposed to exchanges of microflora between the environment
and the digestive system. This increases the risk for the proliferation of an
unfavorable gut microflora or frequent destabilization of the microflora,
which can affect the optimal functioning of the digestive system.
Furthermore, the digestive system of fish and shrimp is the main entry
port for bacterial and viral infections, which remain a major risk for the
profitability of aquaculture production.
Sustainable approaches to modulate the gut microflora in farmed animals
include the use of selected bacteria to inoculate the gut (probiotics),
specific nutrients promoting the development of selected bacterial strains
(prebiotics), and specific natural compounds (mostly derived from yeast
and herbal extracts, so called “phytobiotics”) capable of modulating the
microflora towards a favorable composition, favoring the development of
beneficial bacteria and inhibiting potentially pathogenic microorganisms.
The latter strategies have the advantage of being easily applicable at
40 Innovative approaches to reduce feed cost in aquaculture: optimizing nutrient utilization and gut health