Page 67 - New additives and ingredients in the formulation of aquafeeds

Use of purified extracts from fish viscera as an enzyme
additive in feeds for juvenile marine fish
M. González-Riopedre2, L. Márquez1 , M.P. Sieiro3, U. Vázquez3, J. Maroto3, R. Barcia2
and F.J. Moyano1
1 Dpto. Biología Aplicada. Esc. Sup. de Ingeniería.
Univ. de Almería. Cañada S. Urbano s/n. 04120 - Almería (Spain)
2 Dpto. Bioquímica y Biología Molecular. Fac. Veterinaria.
Univ. Santiago Compostela. Campus Lugo. 27002 - Lugo (Spain)
3 CETMAR. C/ Eduardo Cabello s/n
36208 Vigo, Pontevedra (Spain)
Summary Fish viscera rejected from processing fish captures represents an important
amount of biological material with a very limited industrial utilization. The
possibility of using this material as a source of enzymes to be included
in aquaculture feeds was assessed in the present work. A preliminary
evaluation of total activity, pH and thermal stability of proteases present in
viscera of nearly 20 different species was carried out. Using this information,
extracts of some of selected species were freeze-dried and included as
additive in feeds for juvenile seabream (Sparus aurata). Growth and food
utilization of fish receiving feed including 12 g/kg of the extracts obtained
from preparation the viscera of black scabbardfish (Aphanopus carbo) was
significantly improved. A financial approach of the potential use of this
resource was also developed.
Introduction
and objectives
The discards from fish processing, together with fish by-products, account for
great amounts of biological material produced worldwide annually. Among
these products, the internal organs of fish, which constitute approximately
7.5%of body weight, have been pointed out as interesting potential sources of
different hydrolytic enzymes like pepsin, trypsin, chymotrypsin, gastricins and
elastase. Digestive proteases obtained from marine organisms are especially
interesting to the food and feed industry due to their unique properties,
which include high catalytic efficiency at low reaction temperatures, lower
thermostability, and cold stability (Sahidi and Janak, 2001; Klomklao, 2008).
In addition, the extraction of enzymes from fish processing wastes and their
utilization in the food and feed industry may contribute significantly to
reducing local pollution problems (Blanco et al., 2007)
A great number of studies have demonstrated that marine fish have a
limited activity of some of the main digestive enzymes during their initial
developmental stages (Kolkovski, 2001). On the other hand, there is an
increasing trend to reduce the dependence on live food and current feeding
practicesarebasedinearlyweaningusingcompoundfeedsassoonaspossible.
In spite of the good quality of the ingredients used in most commercial
formulations, the net efficiency obtained from protein and lipids present
in feeds provided during those stages is limited by the poorly developed
Use of purified extracts from fish viscera as an enzyme additive in feeds for juvenile marine fish 65