Fish Silage Research Articles

Acid fish silages. Effect of preheating and addition of phosphoric and citric acids on the biochemical quality

Whole mackerel (Scomber japonicus), without head or spinal bone, were ensiled. In order to observe the preservative effect, two different acid mixtures were used: conventional sulfuric-acetic and phosphoric-citric. To establish the degree of hydrolysis caused by the endogenous enzymes from the fish, enzyme activity was reduced by heating the fish mixture at 60ºC for five minutes, before acid addition. Samples were taken for analysis during 90 days. The pH was stable in all groups throughout the experiment. In the preheated treatment, enzyme activity was lower and the silage more stable, with less percentage of liquid and lower amounts of soluble protein and free amino acids. After 60 days of storage, an increase in total volatile bases was observed in all products, corresponding to the beginning of a decomposition process, probably due to the high temperatures registered during the experiment. It is concluded that the preheated treatment has advantages in comparison to the other treatments, due to the lower hydrolysis which gives lower amounts of soluble protein and free amino acids.

Chemical and nutritional quality of stored fermented fish (tilapia) silage

Abstract Fermented fish silage was produced from minced tilapia ( Oreochromis niloticus ), 15% molasses and 5% Lactobacillus plantarum culture. Initially, batches of the fish silages were fermented at 5, 20, 30 or 35°C for 30 days. The pH declined rapidly at 20, 30 and 35°C but at 5°C, pH decline was slower. Protein solubilization (autolysis) in the fish silages was temperature-dependent as the non-protein nitrogen content (NPN) increased rapidly at higher temperatures. In a second experiment, fish silage was fermented at 30°C for 7 days after which autolysis was halted, then stored at 30°C for 180 days and analysed at intervals. The NPN attained a maximum of 51·4% of total nitrogen content after 180 days. Proximate composition of tilapia silages varied slightly during storage and there was a slight loss of tryptophan during fermentation and storage. The stored wet tilapia silages were blended with soybean meal (1:1, w/w) and dried. The nutritional value of co-dried tilapia silage as a dietary protein supplement for catfish ( Clarias gariepinus ) was studied in digestibility experiments. Although the protein quality of wet tilapia silage was reduced during storage, there were no differences ( P > 0·05) in the apparent protein digestibility coefficients of diets containing co-dried tilapia silages. It is suggested that autolysis in the stored tilapia silages had little effect on proten digestibility in the catfish.

Chemical and nutritional quality of raw, cooked and salted fish silages

Fermented fish silages were prepared from whole tilapia ( Oreochromis niloticus), molasses and Lactobacillus plantarum starter culture. The effects of cooking and addition of 5% salt on the proximate composition, various protein and lipid quality parameters were measured over a 30-day period of incubation at 30°C. The silages were stable during fermentation and storage, and no appreciable loss of nutrient contents was noted. The changes observed were increased degree of autolysis and ammonia production. Addition of salt or cooking of substrate before fermentation prevented continued protein hydrolysis by inhibiting the activity of endogenous autolyzing enzymes and decreased the formation of total volatile bases. The apparent digestibility of dry matter, of nitrogen and of the energy content of silage-based diets for tilapia was higher in both the cooked and salted fish silages than in the raw fish silage.

Silage production from salmon farm mortalities

Fish silage was made from salmon farm mortalities. Citric, formic and propionic acid, as well as combinations of these acids, were used as ensiling media. Stability, liquefaction rate and soluble nitrogen contents were studied. The silages made with 2 or 3% (w/w) of citric acid alone were unable to achieve stability, while the pH increased from 3·8 to 4·5 by day 30 for the 4·5% (w/w) citric acid silage. The pH for the other acids and for the acid combinations was very stable. All of the silages liquified quickly for the first ten days, and then liquefaction levelled off. The amount of soluble nitrogen increased for all the silages, as did the percent liquid. The results indicated that salmon farm mortalities could be used as the raw material in the production of fish silage and a marketable liquid fertilizer.

Autolysed fish silage as a feed ingredient for atlantic salmon ( Salmo Salar)

1. 1. Fish silage made from saithe stored for 2 and 5 months was compared to raw minced saithe as a replacement for parts of the dietary feed protein for Atlantic salmon ( Salmo salar). 2. 2. Weight gain and feed utilization were better in the fish fed the silage stored for 2 months and the raw mince than fish fed the silage stored for 5 months. These fish also showed somewhat better protein utilization. 3. 3. Those fish fed the most hydrolysed feed nitrogen, stored less fat in carcass and fillets, resulting in higher amounts of protein.

Substitution of fish silage protein and a free amino acid mixture for fish meal protein in a chicken diet

AbstractWhite Leghorn chickens were fed a basal diet with about 550 g kg−1 of the protein from fish meal. Graded amounts of fish silage protein or an amino acid mixture simulating fish meal protein were substituted for parts of the dietary fish meal protein. In two experiments 150 and 300 g kg−1 of fish meal protein were replaced by fish silage protein or by an amino acid mixture simulating fish meal. In one experiment graded amounts of 0, 50, 100, 200, 300 and 400 g kg−1 of fish meal protein were replaced by fish silage protein.Growth and feed efficiency were the same or better when some of the protein was from fish silage. The results showed that replacement of dietary fish meal with fish silage did not reduce the dietary quality of the feed for young growing chickens.It is concluded that it might be advantageous to substitute fish silage for some of the fish meal under the experimental conditions used.

The stability of silage from fish mortalities

The stability of salmon silage made with various mixtures of citric and formic acids was studied over an extended period. Two batches of small scale trials with 6 treatments (400 g each), as well as a scale-up experiment (15 kg), were conducted. Liquefaction, pH, ammonia nitrogen and total Kjeldahl nitrogen were studied over the experimental period of 11 months. The microbial population of the silages was also monitored at the end of the experiment. The overall results indicate that the stability of the fish silage during storage is dependent upon the concentrations of the acids, particularly of formic acid. If the silage is to be stored for less than 100 days, the acid concentration can be as low as 0.75% citric acid/0.75% formic acid. For safe storage of approximately 1 year, the fish silage should be made with 0.75% citric acid/1 % formic acid. The results from the scale-up studies made with 0.75% citric acid/1.00% formic acid confirmed the results from the small scale trial. The results also show that the percentage of ammonia nitrogen out of the total Kjeldahl nitrogen in a silage could serve as a stability indicator. All or a large portion of the nitrogen in the unstable silages was in ammonia form. Due to the toxicity of this ammonia, none or very few bacterial colonies were found in the unstable silages.

Utilization of salmon farm mortalities: Fish silage

Laboratory tests were carried out on the production of silage from salmon farm mortalities. Mixtures of citric acid and formic acid of different concentrations were added as ensiling media. The stability, liquefaction and soluble nitrogen levels were studied. The silage made from 0·75% citric acid/ 0·50% formic acid and 1·00% citric acid/0·50% formic acid maintained stability for approximately 30 days at pH 4·5. The pH of the silage made from 0·75% citric acid/0·75% formic acid and 1·00% citric acid/0·75% formic acid remained stable below pH 4·5, while the silage preserved with 0·75% citric acid/1·00% cormic acid and 1·00% citric acid/ 1·00% formic acid remained stable at pH 4·0 or below for the duration of the study period. The liquefaction and soluble nitrogen levels increased quickly within 30 days following preparation. The results indicate that a mixture of citric acid and formic acid can be used to produce good quality fish silage.

Growth of young rats on diets based on fish silage with different degrees of hydrolysis

The effect of storage for up to 1 year on the nutritional value of ensiled cooked and non-cooked minced capelin was determined in growth experiments with young rats. Minced fresh capelin of the same batch was also included. Cooked silage came out best after the storage of 1 year showing both better growth and protein efficiency ratio (PER). There were no significant differences in apparent digestibilities. Rats given the uncooked silage accumulated more glycogen in the liver than the rats given the cooked silage diet ( p < 0.01). The hepatosomatic index and the liver fat content were higher in the rats given cooked silage. No differences were found in hepatic ash and protein contents. The rats given raw minced capelin performed worse than the rats given the silages of up to 180 days of storage, but they performed better than those with 1 year of storage. This was probably due to the procedure used for mixing the diet.

Herring silage as a protein supplement for young cattle

Fish silage made by grinding herring and adding formic acid, β-hydroxytoluene and potassium sorbate was evaluated as a protein supplement for young cattle. Only about 15% of the crude protein in the herring silage was true protein. Ammonia N accounted for 8% of the crude protein and most of the rest was peptides and free amino acids. The crude protein of herring silage was as resistant as fish meal to deamination when fermented in rumen fluid, and more resistant than soybean or casein. The herring silage was readily accepted by Holstein heifers fed hay or grass–legume silage with potatoes (7 kg d−1) and a supplement (1.5 kg d−1). Feed intake and weight gain were similar when the heifers were fed hay with either soybean meal or herring silage but were higher when forage silage replaced the hay. Rumen fluid NH3-N and blood urea levels were normal, even for cattle fed the high non-protein N diet of forage silage with herring silage. The herring silage depressed rumen fluid acetate levels and increased propionate in the heifers fed hay + potatoes, probably because of the unsaturated fatty acids in the herring. Well-made herring silage was a suitable protein supplement for young cattle fed forage and potato diets. Key words: Herring silage, fish silage, potatoes, cattle, protein degradation

Seafood processing wastes ensiled with straw: utilization and intake by sheep

Ensiled mixtures of seafood processing wastes and wheat straw were evaluated. Thirty-six crossbred wethers (average BW = 34 kg) were fed 1) a basal diet (hay and concentrate) alone, or a 1:1 ratio (DM basis) of basal and 2) ensiled fish waste plus straw (70:30, wet basis), 3) ensiled fish waste and straw (51:49), 4) ensiled crab waste plus straw (60:40), 5) ensiled crab waste plus straw (40:60), or 6) ensiled wheat straw (50% moisture). Dry molasses (5%) was included in all ensiled mixtures, and glacial acetic acid (16% vol/wt) was added to the crab waste mixtures. Among diets containing ensiled fish waste, DM digestibility was greater (P less than .01) for the diet containing silate with 70% fish waste than the diet containing 51% fish waste. There was no difference (P greater than .05) in DM digestibility between the two crab waste silages. Apparent digestibility of CP was greater (P less than .01) for diets containing fish than for those containing crab waste. Nitrogen retention (g/d) was positive for sheep receiving all diets but not different among treatments. Apparent absorption of P (g/d) was greater (P less than .01) by sheep fed fish waste silage diets than by those fed crab waste silage diets. Among seafood silages, DMI was greater (P less than .01) for sheep consuming the 60:40 than for those consuming the 40:60 crab waste silage diet and less (P less than .01) for sheep fed the 70:30 than for those fed the 51:49 fish waste silage diet. Seafood processing wastes potentially are valuable to ensile with crop residues for use as ruminant feedstuffs.

Characteristics and identity of obligately aerobic spoilage yeasts from fish silage

Yarrowia (Candida) lipolytica was the predominant organism isolated from the surface film of growth derived from ground hake gurry to which only phosphoric acid was added to give a pH of 4.0. The optimum pH for the crude extracellular protease activity of two distinguishable strains of Y. lipolytica, designated CL1 and CL2, with casein as substrate was 7.0. The optimum temperature of the crude extracellular protease activity from both strains was 50 degrees C. The addition of 2.0% glucose to broth cultures resulted in a significant increase in final cell mass and extracellular protease activity but resulted in a reduction in the units of protease activity per mg of dry cell mass at initial pH values of 5.6 and 7.0 but not an initial pH of 8.0.

Comparison of several organic amendments with a chemical fertilizer for vegetable production

Field research was conducted for seven seasons (1983–1989) on three soil types comparing several organic amendments (dry and liquid fish silage, fish bone meal, blood meal, meat meal, seaweed meal, seaweed extract) with a chemical fertilizer (17-17-17) applied to seeded beans, carrots, peas and sweet corn, and transplanted broccoli, Brussels sprouts, cabbage, cauliflower and lettuce. In most instances, amendments were compared singly with a chemical fertilizer with different rates of nitrogen (N) and methods of application studied each season. In the last season (1989), combinations of fish bone meal, blood meal, meat meal and a seaweed concentrate were compared with pelleted fish silage (ground fish and herring), fish bone meal and a chemical fertilizer. For the cropping seasons 1983–1988, in the majority of comparisons, plants receiving the organic amendments produced crops of comparable yield and size to those from plants receiving the chemical fertilizer. In 1989, plants receiving the chemical fertilizer had significantly higher yields than plants receiving any of the organic treatments. Soil and leaf nutrient values were not consistently affected by the soil type, fertilizer material, rate of N or method of application.

Synthesis of plasteins from fish silage

Synthesis of plasteins from fish silage

Effects on table beet of pre-plant organic and Na-amended inorganic fertilizers

Table beet ( Beta vulgaris L.) seed was planted into field plots treated with either (1) a pre-plant inorganic fertilizer amended with several rates of sodium (Na), (2) a pre-plant application of fish bone meal from a salt fish processing plant or (3) a pre-plant application of liquid fish silage from a fresh fish processing plant. The fish bone meal and liquid fish silage did not receive supplemental Na. The Na-amended fertilizer treatments were first applied to a loamy sand (2–3% organic matter) soil type, and beet root total yields and flavour were not significantly affected by Na additions up to 196 kg ha −1 (500 kg NaCl ha −1) with soil Na ranging from 180 to 270 kg ha −1. In a second season in which Na-amended fertilizer treatments were compared with fish bone meal and liquid fish silage, there were no significant differences in the flavour of beet roots grown in a sandy loam (4–6% organic matter) soil type. Beet leaf and root Na increased, calcium (Ca) and magnesium (Mg) decreased as Na level increased in the pre-plant fertilizer. Leaf potassium (K) decreased with increasing Na in the applied fertilizer. Beet leaf and root Na and soil Ca, Na and phosphorus (P) were higher, and leaf P, K and Ca were lower from plots treated with fish bone meal compared with liquid fish silage. Yield was not affected by Na additions up to 392 kg ha −1 (1000 kg NaCl ha −1) in the pre-plant fertilizer with soil Na ranging from 130 to 140 kg ha −1. Total yield and mean beet root weight across all grades were significantly higher, and the percentage by weight of roots in the small cull size (< 3.8 cm) was significantly lower from plants receiving fish bone meal compared with those receiving liquid fish silage. Results indicate no yield advantage by including Na in the pre-plant fertilizer. These two fish waste products appear to be suitable alternatives to a commercial fertilizer on this sandy loam soil type. The 7–8% Na content of the fish bone meal did not affect beet root yield or flavour when compared with the no Na fertilizer treatment.

Performance of broiler chicks fed on low and high oil fish silages in relation to changes taking place in lipid and protein components

Changes in the protein and lipid components of fish silages made from low oil content fish (LOF; whiting, Gadus merlinger) and high oil content fish (HOF; mackerel, Scromber scombus) were studied during ensiling, drying and subsequent storage. Chicks were fed on diets containing the silages dried on to cassava meal, or fish meal produced from the same batch of fish. The HOF silages had >50% of total N in the form of non-protein N, compared with 18% in the LOF silages; both levels were higher than in corresponding fish meals. Cystine levels in all silages were lower than in the original fish material, the greatest reduction occurring in HOF silage. Tryptophan levels were lower in all processed materials, but the most marked reductions were in LOF silages. Levels of lysine and methionine fell equally in all processed fish materials. The levels of histamine remained low in all fish products. Marked changes occurred in the fatty acid levels of the ensiled fish materials, especially in the HOF silage. The changes were mostly associated with losses of unsaturated fatty acids, in particular C18-3, C18-4, C20-3, C20-4, C20-5, C22-5 and C22-6. Malonaldehyde levels indicated that marked oxidation of the lipid occurred in the HOF silage, this occurred to a much lower extent in LOF silage and to an even lesser extent in fish meals. Addition of antioxidant did not appear to affect these changes. Weight gains of chicks fed on balanced diets containing 4.7 or 9.4% crude protein from HOF silage (9.8 and 19.6% of the dietary dry matter) and 5.2 or 10.4% crude protein from LOF silage (6.8 and 13.5% of the dietary dry matter) were 99, 85 and 98 and 91%, respectively, of the gains achieved with corresponding fish meals. Food conversion ratios for the above dietary treatments were respectively, 97, 103, 101 and 99% of those of chicks fed on fish meals. It was concluded that the differences in chick performance reflected the changes that occurred in the lipid and protein components and the interactions between these components.

The use of fish silage as an ingredient for eel fingerling nutrition

This study was undertaken to test the growth parameters and the body composition of eel fingerlings (1.7 g) fed isoproteic and isocaloric diets with different percentages (10, 15 and 20%) of protein from fish silage. The incorporation of silage in the diet resulted in an increase in the specific growth rate, the food conversion efficiency and the protein efficiency ratio, when compared to a control population fed only a fish and meat meal, as protein source, during a 4-month period. No differences were seen in the effectiveness of the diets incorporating different percentages of fish silage. The increase in growth rate and the presence of greater amounts of lipids in the carcasses of eels receiving silage are partially due to greater food ingestion, owing probably to a different texture of the ration or the possible presence of food attractants. The pattern of amino acids did not differ much between diets, and the essential amino acids were always present in a sufficient amount. Hence the better food conversion efficiency and protein efficiency ratio (PER) of eels on the diets containing silage probably result from the good quality of the fatty acids present in the silage (great percentage of the ω-3 series) and possibly on the greater amount of sodium present.

Total volatile nitrogen — A quality criterion for fish silage?

Total volatile nitrogen (TVN) consisting mainly of trimethylamine (TMA) and ammonia (NH 3), is used as a quality criterion for fish meal and fish meal raw material. Therefore, the significance of TVN and of the NH 3 portion of it as quality criteria for fish silage were studied. Such criteria are required to ensure a wider use of silage in fish feed. Formic acid silages were prepared from fresh raw material of mackerel and of capelin, the latter with varying amounts of acid. In properly preserved silage (stable pH) TVN and NH 3-N increased moderately during storage and amide-N (from glutamine and asparagine) decreased at the same rate. Amide-N was taken to be the difference between NH 3-N before and after weak hydrolysis. The amino acid composition was not significantly affected. As asparagine and glutamine are considered to be dispensable amino acids, this is not expected to affect the nutritional value of the silage. When acid addition was too low, the pH increased during storage and there were large increases in TVN and NH 3-N but a slight decrease in amide-N similar to that found in the other silages. Furthermore, the amino acid composition was affected; arginine and tyrosine seemed most vulnerable. We conclude that amide-N from glutamine and/or asparagine is a major source of the NH 3 formed in properly preserved silage during storage. TVN is thus of limited value as a quality criterion for fish silage.

Utilization of fish silage by rainbow trout ( Salmo gairdneri)

The apparent digestibility and utilization of fish protein subjected to the ensilaging process were compared with fish meal in dry diets fed to rainbow trout ( Salmo gairdneri). During the ensilaging process, a majority of the proteins were converted to peptides, a portion of which was further hydrolyzed to free amino acids. Although apparent digestibility values were higher for the fish silages than for fish meal, the fish silages were not as efficiently utilized for growth. Whole fish and fish processing wastes were found to be equivalent sources of nitrogen provided the degree of autolysis was the same and the diets were otherwise nutritionally balanced. Autolysis was reduced and growth rates enhanced when the ingredients were stored at −5°C prior to ensiling.

Effect of Dietary Addition of Fish Silage, Rape-seed Meal or Vantocil® on Mink Dermal Connective Tissue Components and Fur Quality

Abstract Connective tissue components of samples from skin of minks submitted to 4 different feedings, i.e. (1) control diet, (2, 3 and 4) control diet added respectively filleting scrap as silage; rape-seed meal and Vantocil, a biguanidine product, were analyzed. Skin of animals receiving rape-seed oil (glycosinolates) showed increased content of water, GAG, Hyp, Hyl and decreased fat and Pro, those receiving Vantocil did not show increase of Hyl and those receiving fish silage showed decrease of water and increase of glycosaminoglycans GAG in relation to the control-fed group. Increased fur quality was exhibited by the Vantocil-fed group only. Different content of water was found in skins ready to be sold. Differences in GAG type content, specially hyaluronic acid, known to present high water binding capacity, is suggested. Some of the effects observed are discussed as the result of thyroidal deficiency induced by glycosinolate metabolism.