Physicochemical composition and digestibility of silages from fishery residues in the Atlantic salmon (Salmo salar)

Resumen

Physicochemical composition and in vivo digestibility of chemical and biological silages of fishery residues were determined in Atlantic salmon (Salmo salar) (Linnaeus 1758). The chemical silage was prepared with 2 % of sulfuric acid, 98 and 1 % of formic acid (p/v), and the biological with 12 % beet sugar and 3 % yogurt (Lactobacillus bulgaris (p/p)). The fishes (141.64 + 28.68 g of average weight and 25.91+ 1.70 cm length) were randomly distributed, according to one-way model, into three triplicate treatments (a diet of reference and two experimental diets with each silage). Chromium oxide was used as inert indicator. Feces were collected by decantation in cylinder-conic tanks, of the type Guelph modified. The chemical composition showed that the protein contents of the silages (52.1 y 38.3 %) diminished (P < 0.001) compared with the fresh residues (60.2 %), due to the addition of preservatives in the end product. The digestibility of the nutrients differed according to the silage type. Protein was higher (P < 0.001) in the chemical silage (86.1 %), whereas dry matter (80.34 %), lipids (98.65 %), phosphorus (56.5 %), and energy (87.28 %) were higher in the biological. Ash digestibility did not differ between the silages (51.1 and 54.1 %). It is concluded that the silages of fishery residues varied their chemical composition, but did not change their nutritional value, thereby being an alternative protein source in the formulation of rations for the Atlantic salmon.
Key words: digestibility, fishery silages, salmon, nutritive value