Page 81 - New additives and ingredients in the formulation of aquafeeds

The estimated total saving in feed costs potentially derived from the
inclusion of the CEE in feeds, once a 30% improvement in FCR was applied,
is detailed in Table 7.
Table 7. Estimated consumption and cost of feed under normal conditions or
improved after addition of CEE
Size
range (g)
Weight
increase
(g)
FCR Feed
cosumed
(g)
Feed
cost
(€/kg)
Feed
cost
(€)
FCR
improved
Feed
cosumed
(g)
Feed
saving
(g)
Cost
saving
(€)
0.5-15 14.5 2 30 1,2 0.04 1.71 25 5.23 0.01
15-150 135 2.3 320 1 0.32 1.96 265 54.8 0.05
150-300 150 2.6 400 0,85 0.34 2.22 333 66.9 0.06
TOTAL
by fish 299.5 750 0.696 623.1 126.9 0.1
by kg 998.3 2,500 2.32 2,077 423 0.39
On the other hand, an increase of growth rate by 10% should represent an
equivalent reduction in the time required by fish to reach market size. If an
average production cycle lasts 330 days (11 months), this should mean nearly
one month (33 days) less time and hence an additional saving of monthly
costs. Considering than average total production cost are nearly 3.3 €/kg,
monthly cost may be estimated in 0.3 €/kg, this being the additional saving
derived from the use of CEE in feeds.
As a resume, total saving in production cost should be 0.39€ (feed) + 0.3€
(cycle shortening) = 0.69 €/kg of fish produced. Clearly, the estimated cost
of including the enzyme additive (11.40 €/kg) exceeds by far the expected
benefits. In other words, the potential use of the CEE should be only profitable
if its inclusion in feeds do not increase cost more than 0.5-0.6 €/kg. This
means a reduction by 20 times of the costs estimated in the present study.
Conclusions Fish viscera can be used to obtain and prepare a product with enzymatic
activity that can be included as additive in fish feeds.
The selection of the most suitable species as a potential source of enzymes
should consider both its availability (regular supply) as well as biochemical
aspects (stability of the enzymes under awide range of pH and temperature).
After evaluation of 19 species, enzymes obtained from the viscera of
Sebastes spp., Aphanopus carbo and Illex argentinus seem to be potential
candidates for their inclusion as additives in fish feeds.
The use of a semipurified extract obtained from viscera of Aphanopus carbo
significantly improved growth and food conversion in juveniles of gilthead
seabream (Sparus aurata ) when included at 12 g/kg feed.
Use of purified extracts from fish viscera as an enzyme additive in feeds for juvenile marine fish 79