186
J.G. Bell and R. Waagbø
6.1 Introduction
The rapid growth of aquaculture production worldwide, estimated to be around
10.5% per annum over the last 10 years, (Tacon 2003), has meant that demand
for extruded aquafeeds has increased in parallel with production. The culture of
carnivorous species in Europe, principally Atlantic salmon (Salmo salar),
rainbow trout (Oncorhynchus mykiss), European sea bass (Dicentrarchus
labrax) and gilthead sea bream (Sparus aurata), has meant that aquafeed formulations have contained relatively large amounts of both fish meal (FM) and
fish oil (FO) derived from marine feed grade fisheries. Until recently this has
been regarded as sound practice as fish meal is rich in essential amino acids, is
readily accepted and digested by fish and has been readily available and
relatively cheap. In addition, FO meets the high requirements of fish for n-3
essential fatty acids and, while freshwater fish and salmonids can convert
18:3n-3 to 20:5n-3 and 22:6n-3, but thrive on 20:5n-3 and 22:6n-3, marine fish
cannot perform this conversion and have an absolute requirement for 20:5n-3
and 22:6n-3 (Sargent et al. 2002).
Fish meal and oil are obtained from feed grade fisheries that have effectively
reached their sustainable limits and production of FM and FO has remained
relatively stable for the last 20 years (Pike 2005). Previous estimates that global FO
demand would outstrip production by 2010 or earlier (Barlow and Pike 2001) have
now been revised but current estimates suggest that by 2010 more than 85% of the
fish oil will be consumed in aquafeed production (Tacon 2004). Therefore, it is vital
to reduce dependence on marine raw materials and that sustainable aquafeeds are
developed using more terrestrial plant products. An additional reason to include
more plant products, especially vegetable oils (VO), is because levels of persistent
organic pollutants, principally dioxins/furans and polychlorinated biphenyls
(PCBs), in some Northern hemisphere FO may breach new EU limits and prevent
their use in aquafeeds (Easton et al. 2002; Foran et al. 2005; EC, 2006b).
Over the last 5–10 years considerable research has been conducted on testing
replacements for FO and FM in a range of cultured freshwater, anadromous and
marine finfish species. A large amount of data on FO and FM replacement has
arisen from the EU Framework 5 projects, Researching Alternatives to Fish Oil in
Aquaculture (RAFOA, www.rafoa.stir.ac.uk) and Perspectives on Plant Protein
Alternatives (PEPPA, www.st-pee.inra.fr/ici/stpee/nut/peppa/peppa.htm). RAFOA
established that salmonids could be cultured on diets where 100% of the FO is
replaced by single VO, or a VO blend and that for bass and bream replacement of
up to 60% of FO showed no detrimental effects on growth. PEPPA established that
trout and bream can be cultured with 75% replacement of FM, by plant products
with no loss of growth performance. However, such high levels of FO replacement
can only be achieved provided essential fatty acid (EFA) levels are maintained by
the inclusion of adequate FM levels. Likewise, high levels of FM replacement were
achieved in feeds using FO as oil source and, thus, future studies seeking to replace
both FM and FO may prove more challenging.
J.G. Bell and R. Waagbø
6.1 Introduction
The rapid growth of aquaculture production worldwide, estimated to be around
10.5% per annum over the last 10 years, (Tacon 2003), has meant that demand
for extruded aquafeeds has increased in parallel with production. The culture of
carnivorous species in Europe, principally Atlantic salmon (Salmo salar),
rainbow trout (Oncorhynchus mykiss), European sea bass (Dicentrarchus
labrax) and gilthead sea bream (Sparus aurata), has meant that aquafeed formulations have contained relatively large amounts of both fish meal (FM) and
fish oil (FO) derived from marine feed grade fisheries. Until recently this has
been regarded as sound practice as fish meal is rich in essential amino acids, is
readily accepted and digested by fish and has been readily available and
relatively cheap. In addition, FO meets the high requirements of fish for n-3
essential fatty acids and, while freshwater fish and salmonids can convert
18:3n-3 to 20:5n-3 and 22:6n-3, but thrive on 20:5n-3 and 22:6n-3, marine fish
cannot perform this conversion and have an absolute requirement for 20:5n-3
and 22:6n-3 (Sargent et al. 2002).
Fish meal and oil are obtained from feed grade fisheries that have effectively
reached their sustainable limits and production of FM and FO has remained
relatively stable for the last 20 years (Pike 2005). Previous estimates that global FO
demand would outstrip production by 2010 or earlier (Barlow and Pike 2001) have
now been revised but current estimates suggest that by 2010 more than 85% of the
fish oil will be consumed in aquafeed production (Tacon 2004). Therefore, it is vital
to reduce dependence on marine raw materials and that sustainable aquafeeds are
developed using more terrestrial plant products. An additional reason to include
more plant products, especially vegetable oils (VO), is because levels of persistent
organic pollutants, principally dioxins/furans and polychlorinated biphenyls
(PCBs), in some Northern hemisphere FO may breach new EU limits and prevent
their use in aquafeeds (Easton et al. 2002; Foran et al. 2005; EC, 2006b).
Over the last 5–10 years considerable research has been conducted on testing
replacements for FO and FM in a range of cultured freshwater, anadromous and
marine finfish species. A large amount of data on FO and FM replacement has
arisen from the EU Framework 5 projects, Researching Alternatives to Fish Oil in
Aquaculture (RAFOA, www.rafoa.stir.ac.uk) and Perspectives on Plant Protein
Alternatives (PEPPA, www.st-pee.inra.fr/ici/stpee/nut/peppa/peppa.htm). RAFOA
established that salmonids could be cultured on diets where 100% of the FO is
replaced by single VO, or a VO blend and that for bass and bream replacement of
up to 60% of FO showed no detrimental effects on growth. PEPPA established that
trout and bream can be cultured with 75% replacement of FM, by plant products
with no loss of growth performance. However, such high levels of FO replacement
can only be achieved provided essential fatty acid (EFA) levels are maintained by
the inclusion of adequate FM levels. Likewise, high levels of FM replacement were
achieved in feeds using FO as oil source and, thus, future studies seeking to replace
both FM and FO may prove more challenging.