230 Fish as feed inputs for aquaculture – Practices, sustainability and implications
TABLE 13
Typical composition of the main feeds used in European aquaculture
Feed type Protein % Oil % Typical FCR*
Salmon starter diets 50–55 14–23 0.90–1.00
Salmon grower diets 34–50 22–38 1.20–1.30
Trout starter diets 50–57 14–22 0.80–0.95
Trout grower diets 38–50 8–33 0.90–1.30
Other finfish diets Marine fish 50–60 12–24
1.10–1.40
Freshwater fish 31–55 7–18
*Food conversion ratio.
Source: J Nelson, Agricultural Industries Confederation (AIC), personal communication, 2004Fishmeal
Based on the current trends in production discussed in the previous section, a tentative
forecast can be made of likely fishmeal usage by European aquaculture over the next
ten years (Table 14). This table indicates that fishmeal usage will increase from the
present level of around 615 000 tonnes to about 630 000 tonnes in 2015.The increase in demand for fishmeal is not particularly dramatic and is at a lower
pace than the predicted increase in production, mainly due to increased efficiencies in
fishmeal and fish oil usage that result from improved feed formulation and delivery. The
rate at which fishmeal is included in aquaculture diets is expected to drop over the next
decade as increasing levels of substitution with vegetable proteins and oils occurs. In
addition, continued research into the dietary requirements of particular species reared
under particular conditions will refine formulations and improve feed delivery that,
with the increased use of automated feeding and consumption monitoring systems, will
lead to potential improvements in food conversion ratios (FCRs).Fish oil
The use of fish oil by European aquaculture is predicted to rise at a slightly higher rate
than the use of fishmeal (8 percent as opposed to just over 2 percent), as inclusion rates
are set to increase slightly (Table 15). This table indicates that European demand for
fish oils for aquaculture will rise to almost 343 000 tonnes by 2015 from the current
level of almost 305 000 tonnes.3.3.2 Fishmeal and fish oil use in agriculture
The agriculture sector uses predominantly Peruvian and Icelandic fishmeal, with
fishmeal from Morocco and other minor sources making up the balance. With fishmeal
and fish oil production predicted to remain stable over the next decade and the
proportion being utilized by aquaculture increasing considerably, there is likely to be
a fall in the proportion used by agriculture (Table 16).
For most domestic animal species, fishmeal is included as a feed supplement in
order to increase the protein content of the diet and to provide essential minerals
and vitamins. In general, fishmeal is considered an excellent protein source for all
animal species (including fish), being rich in essential amino acids for non-ruminants,
particularly lysine, cystine, methionine and tryptophan, which are key limiting amino
acids for growth and productivity of the major farmed species. Manipulation of protein
quality during fishmeal production is important in the manufacture of specialist feed
supplements. For example, low temperature (high digestibility and biological value,
BV) products are used in diets for fish, young piglets and poultry, whereas products
for ruminant diets are heated differently to reduce the breakdown of the protein by the
rumen microflora (and thus increase the content of rumen undegradable protein, RUP)
and to reduce the soluble nitrogen content.