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Fish silage, fishery wasteDescription:The ensiling of fishery waste can be an easy and economical methods of preserving fishery waste, so that it can be fed at a later time. This can be especially useful when only small amounts of fishery waste is available. Several different methods can be used to produce fish silage: 1) adding inorganic or organic acids to lower the pH to a point where it is stable; 2) addition of inorganic or organic acids to lower the pH to a point at which intrinsic enzymes will liquefy (which are normally most active around pH 4 and at temperatures between 35 to 40 o C) the the protein, prior to adding additional acid to stabilize the pH to a level that is suitable for storage); and 3) adding carbohydrates and allow fermentation to occur, so that enough acid is produced to stabilize the silage. Various acid stabilization methods will be described in later sections. The resultant liquefied product can then be screened to remove bones and reduce the ash content. Mold inhibitors are often added to control surface mold growth. Quality of substrate used to prepare the fish silage is directly related to the quality of the resultant fish silage. If silage is prepared from partially decomposed materials then the histamine levels in the fish silage will reflex what was present initially. Caution:Histamine levels can be a problem if the fish waste is allow to decompose prior to being ensiling. Source: Can be prepared from by-catch or fishery waste that remains after the human product has been removed. Well suited for handling small quantities of fish wastes. Feeding Experiments:Primarily used in feeding of monogastric animals (poultry, swine, fish, etc.) and only fed to a limited extent to ruminant animals. Dried fish silage replaced soybean meal no difference in gain or feed conversion was observed in broilers (13)(AGRIS 94-100560)(Ramlal, 1991). Replacement of 50 % of the fish meal in layer diets was not shown to affect egg flavor or quality (12)(AGRIS 91-015272)(Saowanit, 1987). When fish silage replaced fish meal performance in ducks was reduced, but when the silage was dried it’s performance was similar (8)(AGRIS 90-099921)(Rahardjo, 1984). Thiamine seems to not be present in adequate amounts in fish silage to support normal growth in ducks (8)(AGRIS 90-099921) (Rahardjo, 1984). Formic acid was added at the rate of 2.5 % (w/w) to prepare fish silage made from fish waste (heads, guts, remains after deboning) was found to increase growth and feed conversion when compared to fish meal when fed to swine (11)(AGRIS 92-055955) (Trevino, 1981). Fish silage was found to give better growth than fish meal when fed to carp (7)(AGRIS 90-102075) (Djajasewaka, 1986). Nutrient digestibility in fish silage is high (4)(AGRIS 1998-033793) (Cetinkaya, 1995). Tilapia fish silage prepared with 4 % formic acid was found to be comparable to imported Peruvian Fish Meal when compared in growing / finishing swine (1)(AGRIS 88-046664) (Olivo, 1985). Fish silage fed to sheep has high digestibility for DM, CP and phosphorus (2)(AGRIS 92-067018) (Samuels, 1991). Feeding and Handling Characteristics:Production of fish silage is a viable alternative to fish meal, especially in location where small amount of fishery waste or by-catch is produced (9)(AGRIS 89-052834)(Abdullah, 1983). Enzymes present in the fish waste will digest and liquefy the protein associated with the fish waste (4)(AGRIS 1998-033793) (Cetinkaya, 1995). Organic or inorganic acids can be used lower the pH of the fish silage to a pH that is stable for storage (4)(AGRIS 1998-033793)(Cetinkaya, 1995). Fish silage was prepared by boiling fishery waste and then adding enzymes to digest the material and then the pH was adjusted by adding acid (6)(AGRIS 1999-055241) (Naret, 1995). Acidifying fish silage by adding an equivalent percentage of either H3PO4, formic acid and acetic acid were evaluated, H3PO4 resulted in the lowest pH and lowest NH3-N content in the silage (5)(AGRIS 2000-014277)(Jokic, 1998). Formic acid resulted in the highest content of NH3-N (5)(AGRIS 2000-014277)(Jokic, 1998). Formic acid (4%) treated fish silage was found to be superior to acetic or lactic acid preserved silages (1)(AGRIS 88-046664)(Olivo, 1985). Sun drying of fish silage that has been combined with rice bran or wheat bran were found to be viable options, but deoiling it was a problem (3)(AGRIS 84-044838)(Ganegoda, 1982). Nutrient Characteristics:
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