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Fish silage for feeding livestock

Preparation methodology
Chemical composition
Use for feeding

R. Pérez

The author can be contacted at Departamento de Producciones Complementarias, Ministerio del Azúcar, Havana, Cuba.

Preserving by-catch (scrap) fish and fish wastes or residues (heads and offal) in the form of silage and using them as feedstuff for livestock is not a new idea (Cameron, 1962; Zaitsev et al., 1969; Smith, 1977). The problem lies in the commercial implementation. Fish silage, unlike fish-meal, does not come in a bag; it is semi-liquid, messy and smelly. This means that most livestock producers will require prior convincing, sufficient training and extreme perseverance before it can be successfully incorporated into animal feeding systems. Indeed, perhaps one of the reasons for the need for this article is that, until now, fish silage has remained mostly an academic question. Furthermore, while neither fishermen nor fish processors tend to be livestock producers, and vice versa, the fact remains that the edible flesh of most types of fish represents only 40 percent of the total weight, which means that, if not converted into fish-meal, some 60 percent could be used as a protein feed resource. One country that rapidly adopted the technique for producing fish silage, particularly for feeding beef cattle, is Cuba. In the beginning, acid silage was promoted (Alvarez, 1972; MINAG, 1975), but today, for both economic and safety reasons in the preparation procedure, by-catch and fish wastes are simply preserved in molasses.

Preparation methodology

The technique for making fish silage is cheap and simple (Windsor and Barlow, 1981). It can be made from by-catch or fish wastes, which are preferably chopped or ground prior to the addition of organic or mineral acids or of a carbohydrate source for fermentation. The presence of mineral or organic acids or the lactic fermentation decreases the pH, which inhibits the growth of bacteria, and hence enables long-term storage of the raw material. Fish silage made with organic or mineral acids is commonly referred to as acid fish silage, while that which requires the addition of a source of carbohydrates and anaerobic storage conditions is known as fermented or biological fish silage.

1 - Liver-protein utilization values for different protein sources - Valeurs d'utilisation des protéines dans le foie pour différentes sources de protéines - Valores de la utilización de las proteínas a nivel hepático de distintas fuentes


Fish silage


Saccharomyces yeast

Torula yeast


Liver-protein utilization (%)






Source: Alvarez, 1972.
ab Mean in same row without letter in common differ at p<.05.

2 - Variation in pH of fish silage made with different sulphuric acid solutions and substrates - Variation du pH de l'ensilage de poisson fait avec différentes solutions d'acide sulfurique et différents substrats - Variación del pH del ensilaje del pescado con distintas soluciones de ácido sulfúrico y sustratos

Sulphuric acid solution (ml): raw material (kg)

Fish silage

Fish silage mixed 1:1 (v/v) with final molasses


72 hours

35 ml:by-catch




35 ml:fish wastes




40 ml:by-catch




40 ml:fish wastes




50 ml:by-catch




50 ml:fish wastes




Source: Penedo, Cisneros & Rodríguez, 1986.

In both types of silage, during storage, endogenous, proteolytic enzymes break down the tissue protein to low molecular weight peptides and amino acids that remain soluble and stable (Green, Wiseman and Cole, 1983). Apparently, under normal storage conditions, degradation of the amino acids is not of great importance. In fact, Gildberg and Raa (1977) showed that, in fish silage stored for up to 220 days, less than 8 percent of amino nitrogen is released as ammonia. Nevertheless, at temperatures exceeding 30°C, tryptophan, methionine and histidine tend to decompose (Machin, 1990).

Another way to preserve by-catch and fish wastes is to mix and store them directly in sugar-cane molasses. A brief description of all three methods follows.

Acid silage

Acid fish silage is made from by-catch or fish wastes, which are preferably chopped or ground, placed in non-metallic vats, mixed with an acid solution and stirred several times daily for three to five days until liquefied (Cervantes, 1979). It can contain from 27 percent (Machin, Young and Crean, 1982) to 35 percent (Domínguez, 1990) dry matter. The lowered pH prevents bacterial putrefaction, which allows the silage to be stored for several months. Acids that can be used in this process are the organic acids propionic and formic (Rattagool, Surachatmrongratane and Wongchinde, 1980; Wiseman, Green and Cole, 1982; Machin, Young and Crean, 1982), and certain mineral acids, either sulphuric or hydrochloric (Alvarez, 1972; Machin, 1990).

In Cuba, Alvarez (1972) used a concentrated solution of sulphuric acid and water (1:1 ratio by volume) to determine the optimal proportion of acid solution for preserving fish wastes. The objective was to compare the nutritive value of the protein in fish waste silage to those of fish-meal, two types of yeast and a casein (control). For this purpose, liver-protein utilization values were determined in rats (Table 1). The fish wastes were not chopped and the quantities of acid solution used were 20,30,40,50,60,70, 80 and 90 ml/kg of raw material. The mixture offish wastes and acid solution was stored in closed plastic tanks and stirred for three minutes, three times a day, for a period of five days. The amount of 60 ml of acid solution per 1 kg of fresh fish waste was selected as optimum. After five days, the pH of the mixture was 1.8, and prior to use it was neutralized to a pH of 5 by the addition of calcium carbonate. Later, Cervantes (1979) showed that whole by-catch could also be preserved using the same concentration and proportion of sulphuric acid solution, 60 ml/1 kg of a 1:1 mixture. If ground fish wastes were used, however, they could be preserved using half the amount of acid solution, only 30 ml/1 kg.

In 1986, Penedo, Cisneros and Rodríguez compared by-catch to fish wastes as raw material for fish silage. Three different amounts of commercial sulphuric acid -35, 40 and 50 ml - were added to 700 ml of water. Each solution was subsequently mixed with 1 kg of either by-catch or fish wastes. After three days, the silage material was combined with an equal amount (volume) of final molasses (Table 2). It was emphasized that, if the silage was to be used within three days, the 35 ml solution would be sufficient; if it was to be kept for 15 days, the 40 ml; and if it was to be stored for one month or more, the 50 ml. The authors stated that by-catch was inferior to fish wastes because it contained more than 9 percent of extraneous, calcareous matter, mostly in the form of large crustaceans. The problem was that the acid solution could not easily attack the organic matter within the shell causing putrefaction and a disagreeable odour. Domínguez (1988) suggested that one general rule when using other types of acid might be to adjust the pH to below 4.

In Cuba, between 20 000 and 25 000 tonnes of acid fish silage was produced annually from 1968 to 1990, in seven factories along the coast, set up and run by the Ministry of Agriculture to provide a protein-rich feed for ruminants. The process used for both by-catch and fish wastes, or a combination of the two, was based on the use of concentrated commercial sulphuric acid and not on the use of the previously described acid solution. This was because of the large size of the operation, easily between 5 and 8 tonnes per batch. The raw material, which itself contained a considerable amount of water, was placed in concrete tanks situated in sheds and then completely covered with water (at least 2.5 cm above the fish line) before the concentrated commercial sulphuric acid was added. The acid was added at the rate of 8 to 9 percent by weight or 5 percent by volume (1 litre weighed 1.75 kg), which represented 50 litres or 90 kg of commercial sulphuric acid per tonne of raw material.

Over a period of three days, the mixture was stirred two or three times a day. If the raw material happened to contain a significant amount of large pieces or shellfish, they were removed by hand and/or the number of stirring days was adjusted accordingly. After the material had liquefied, the oil, which had separated and surfaced, was skimmed off for use in concentrate rations for calves. The final product, commonly referred to as protein paste, was neutralized to a pH of 6 by adding calcium hydroxide or carbonate. It was used in commercial cattle feedlot operations in a ration of 1:1 with final molasses or mixed 1:1 with wheat bran as a feedstuff for calves (MINAG, 1975).

Finally, in a review of the subject, Green, Wiseman and Cole (1983) defended the use of organic acids, mainly arguing that preservation could be achieved at a higher pH and therefore the silage would not require neutralization prior to use. It was emphasized that the wastes should be chopped into pieces of 4 mm in size prior to treatment with an 85 percent solution of formic acid or a 1:1 mixture of formic and propionic acid, included at 3.5 percent (Wiseman, Green and Cole, 1982, and Rattagool, Surachatmrongratane and Wongchinde, 1980, cited by Green, Wiseman and Cole, 1983).

Fermented silage

The principle of fermented silage is similar to that of acid silage; preservation is the result of acidity arising from the growth of lactic acid-producing bacteria. By-catch or fish wastes, preferably chopped or minced, are placed in non-metallic vats and mixed with a single carbohydrate source, such as cassava, sweet potato or molasses or a mixture of these, and stored airtight. In order for fermentation to start almost immediately, the addition of 20 to 30 percent of molasses has been recommended (Domínguez, 1988). Periodic agitation and temperatures of at least 20°C tend to induce rapid liquefaction of the raw material (Green, Wiseman and Cole, 1983).

Most of the experiences in the preparation and use of biological fish silage in Latin America were summarized in the proceedings of the FAO Second Expert Consultation on Technology of Fish Products (FAO, 1989). Various kinds offish residues and by-catch have been preserved as silage using several sources of carbohydrates for fermentation by natural occurrence or inoculated microorganisms. The results of the inclusion offish silage in the diets of pigs, chickens and beef cattle have demonstrated that it is a valuable source of protein that can, in most cases, replace fish-meal or other traditional protein sources.

Some results of feeding fermented silage to pigs are presented in Table 9. The silage was prepared using a 5 percent lactobacillus culture mixed with 60 percent by-catch, 30 percent ground maize and 5 percent molasses (Tibbetts et al., 1981). Later, Domínguez (1988) suggested that if the objective was to prepare a complete fish silage ration, using roots as the principal source of carbohydrates, then the following general formula might be used (percentage air-dry): roots, 30 to 50 percent; molasses, 10 percent; and fish wastes, 40 to 60 percent. In Viet Nam, fish silage made from shrimp heads, fresh blood (abattoir) and molasses in proportions of 5:3:2, respectively, and fermented for a period of ten days reportedly had a pH of between 4.3 and 4.5 (Table 3) as well as a "pinkish colour, nice flavour and soft texture" (AHRI, 1993).

Molasses preservation of by-catch and fish wastes

The idea that "whole" fish wastes could be preserved directly in cane molasses was first proposed during an FAO Expert Consultation in 1986 to promote sugar cane as animal feed (Pérez, 1988). At that time, it was suggested that the silage could be used as a source of protein for geese. More recently, trials have shown that, in order to expedite the ensiling process, the raw material should preferably be chopped or ground prior to mixing with an equal amount (weight) of molasses (4.5 litres of final molasses weighs 5.5 kg). It has also been suggested that, although the osmotic pressure of the molasses causes an initial dehydration of the raw tissue, an acidic fermentation also occurs, which tends to preserve this material (Domínguez, 1988; IAV, 1994). One recommendation is that, if the raw material is left whole, it should be completely submerged in molasses. To do this, a wire net should be stretched over the surface of the mixture so that weights can be placed on top (Domínguez, 1990; Pérez, 1993). The mixture should be stirred twice daily, over approximately five to seven days.

In Morocco, a mixture (50:50 w/w) of molasses and drained ground fish wastes, left uncovered and stirred daily, required a period often days to produce a stable final product with a pH of 4.5. The fish silage was then formed into blocks in order to have solid feeding material for sheep, goats, horses and camels. The procedure involved adding a 1 percent supplement of minerals and vitamins and about 20 percent ground straw. The blocks of approximately 7 to 8 kg were dried in the sun for two to four days. One further recommendation was to use about 5 percent cement during preparation of the blocks (IAV, 1994).

3 - Fermentation of shrimp-head silage: variation in pH with timea - Fermentation de l'ensilage de têtes de crevettes: variation du pH dans le temps - Fermentación de ensilaje de cabezas de camarón: variación del pH con el tiempo

Week 1

Week 2

Week 3

Shrimp heads and molassesb




Fresh blood and molassesb




Shrimp heads, blood and molasses (5:3:2)c




Source: AHRI, 1993.
a Remained low or increased its acidity after 21 days.
b Ratio not reported.
c Percentage air-dry proportion.

Shrimp head-molasses silage in Viet Nam - Ensilage de têtes de crevettes-mélasse au Viet Nam - Ensilaje de cabezas de camarón y melaza en Viet Nam

Fish silage being made - Préparation de l'ensilage de poisson - Ensilaje de pescado en fase de elaboración

By-catch fish from shrimp fishing - Captures accessoires de poisson provenant de la pêche à la crevette - Pesca acompañante del camarón - Photo/foto: M. Ottati

Pigs feeding on diets containing fish silage - Ration pour porcs contenant de l'ensilage de poisson - Cerdos alimentándose con ensilaje de pescado - Photo/foto: H. Lupin

4 - The bacteriostatic effect of sugar-cane B molasses on Escherichia coli and Salmonella thyphimurium - Effet bactériostatique de la mélasse B de canne à sucre sur Escherichia coli et Salmonella thyphimurium - Efecto bacteriostático de la melaza B de la caña de azúcar sobre Escherichia coli y Salmonella thyphimurium


Storage (days)




(colony-forming units/g)

E. coli


1.2 x 106




1.1 x 106

2.3 x 102


S. thyphimurium


3.3 x 106




3.5 x 106

2.6 x 102


Source: Martínez (in press).

In addition to final molasses being used to preserve raw fish tissue as protein paste for formulating livestock rations, both by-catch and fish wastes (chopped or ground) preserved directly in sugar-cane B molasses in a proportion of 2:1 by weight (air-dry basis) of molasses to raw material offers an interesting option for preserving fish wastes as well as for generating a complete liquid ration of between 8 and 10 percent crude protein in dry matter for fattening pigs. In this regard, Martínez (in press) showed the bacteriostatic effect of B molasses on Escherichia coli and Salmonella thyphimurium (Table 4).

Chemical composition

The data in Table 5 refer to the chemical composition of different types of fish silage. Surprisingly, these data do not support the general hypothesis that silage made from by-catch is superior to that produced from fish wastes. One reason for this may be the average size of the individual pieces of raw material. By-catch refers to fish that are "caught incidentally and cannot be sold for human consumption", while fish wastes refer to the "remaining heads, skin, bone and viscera obtained from commercial fish processors" (Green, Wise and Cole, 1983). In addition to fish silage, as such, Meinke (1974) reported the chemical composition of fresh by-catch obtained from the Gulf of Mexico as (percentage air-dry): crude protein, 14.4 to 20.8 percent; oil, 1.2 to 14.5 percent; ash, 3.2 to 8.8 percent; and moisture, 67.3 to 81.5 percent.

The amino acid composition offish silage is presented in Table 6. Lysine, threonine and sulphur containing amino acids are present in high levels, as they are in fish-meal. Consequently, fish silage would appear to be an excellent protein supplement for non-conventional livestock feeding systems.

A review of the use of fish silage for pigs shows that the energy and nitrogen in fish silage are highly digestible (Table 7). In fact, Whittemore and Taylor (1976) reported that the digestible energy and nitrogen were higher in diets containing fish silage than in those using fish-meal.

Use for feeding

The following information shows how fish silage can be used for feeding both non-ruminants and ruminants.


The data in Table 8 show the results of using by-catch and fish-waste acid silage preserved with 60 and 30 ml/kg of sulphuric acid solution, respectively, as substitutes for the crude protein in fish-meal for growing/finishing pigs fed on a diet based on processed swill and molasses (Cervantes, 1979). At the highest level of protein substitution (100 percent), 12.3 percent of silage replaced 9.3 percent of fish-meal in terms of total dietary dry matter. Performance was significantly lower when 100 percent of the fish-meal was replaced by silage, and this was attributed to the palatability of the ration, which significantly affected feed intake. More recently, it has been shown that high levels of final molasses can affect overall pig performance, which perhaps also contributed to the relatively poor results in this experiment (Figueroa and Ly, 1990). In addition to normal carcass-quality measurements, various organoleptic evaluations were performed: odour, taste, juiciness and texture. It appeared that treatment had no effect on these parameters and it was concluded that fish silage could be used to provide up to 50 percent of the protein supplied by fish-meal in this type of feeding system.

5 - Chemical composition of different substrates used in fish silage - Composition chimique de divers substrats utilisés dans l'ensilage de poisson - Composición química de distintos sustratos utilizados en el ensilaje de pescado



Crude protein




(percentage dry matter)






Rattagool, Surachatmrongratane & Wongchinde (1980)*

United Kingdom




Green, Wiseman & Cole (1983)





Cervantes (1979)




Tatterton & Windsor (1974)*

Fish wastes





Whittemore & Taylor (1976)*





Tatterton & Windsor (1974)*





Disney et al. (1978)*





Green, Wiseman & Cole (1983)










Cervantes (1979)


Cuba/by-catch and fish wastes




Penedo, Cisneros & Rodríguez (1986)

* Cited by Green, Wiseman & Cole, 1983.

6 - Amino acid composition of fish silage - Teneur en acides aminés de l'ensilage de poisson - Composición de aminoácidos del ensilaje de pescado

Amino acid

Smith & Adamson (1976)

Whittemore & Taylor (1976)






































* Lysine, methionine and cystine: 5.8, 2.7 and 1.0 g/kg, respectively; in leftover liquid (6% dry matter) portion these same values were reported as 3.3, 1.3 and 0.6. respectively (Department of Animal Nutrition, University of Rostock, Germany, cited by Penedo, Cisneros & Rodríguez, 1986).

7 - Nutritive value of fish silage for pigs - Valeur nutritive de l'ensilage de poisson pour les porcs - Valor nutritivo del ensilaje de pescado para los cerdos


Digestible energy
(MJ/kg DM)

Metabolizable energy
(MJ/kg DM)

Crude protein
(% DM)

Nitrogen digestibility
(% total N)


- mackerel





- whiting





De-oiled, herring offalb





Source: aGreen, Wiseman & Cole, 1983; bWhittemore & Taylor, 1976.
DM = dry matter.

8 - Substitution of protein in fish-meal for acid fish silage in dietsa based on processed swill and molasses for growing/finishing pigs - Remplacement des protéines de la farine de poisson par de l'ensilage acide de poisson dans les rations à base d'eaux grasses traitées et de mélasse pour les porcs en croissance/finition - Sustitución de las proteínas de la harina de pescado por ensilaje de pescado ácido en la alimentación de cerdos en crecimiento y engorde a base de desperdicios y melaza

Substitution of crude protein of fish-meal

Feed intake
(kg DM/day)

Average daily gain

Dry-matter feed conversion

By-catch, whole: preserved with 60 ml/kg sulphuric acid solutionb

















Fish wastes, ground: preserved with 30 ml/kg sulphuric acid solutionc

















Source: Cervantes, 1979.
aBasal diet (% DM): processed swill, 47%; final molasses, 44%; and fish-meal, 9%. The crude protein in DM of swill and silage was, respectively, 22% and 57%.
b30 to 90 kg.
c25 to 80 kg.
DM = dry matter.

9 - Use of fermented or acid silage for growing/finishing pigs - Utilisation d'ensilage fermenté ou acide pour les porcs en croissance/finition - Uso de ensilaje fermentado o ácido para cerdos en crecimiento y engorde


Percentage dry matter

Average daily gain

Dry-matter feed conversion


By-catch fermented silagea




Tibbetts et al. (1981)










By-catch acid silageb




Machin, Young & Crean (1982)










a Fermented silage: lactobaccilus culture, 5%; by-catch, 60%; ground maize, 30%; and molasses, 5%; liveweight 27 to 95 kg.
b 25 to 80 kg.

The data in Table 9 are somewhat contradictory. In the first experiment, the use of more than 6 percent fermented silage affected growth and feed efficiency (Tibbetts et al., 1981). In the second trial, performance generally improved when increasing amounts of by-catch acid silage were used in diets based on 60 percent sorghum grain (Machin, Young and Crean, 1982). These observations tend to support the conclusion drawn by Green, Wiseman and Cole (1983) with reference to the cause of discrepancy among researchers. These authors recognized the "diversity with respect to both the type of fish tissue and the silage method employed" and emphasized that feed-conversion efficiency of pigs fed fish silage is very likely related to the balance of essential amino acids in the silage, which is dependent on the type of fish used. They referred to experiments in which lysine and other essential amino acids were adequate and in which fish silage diets produced better feed conversions than soybean meal diets.

More recently in Viet Nam, the nutritional value of fermented silage made from shrimp heads, blood and molasses was compared with that of fish-meal in 17 percent crude-protein rations for growing pigs. The silage and fish-meal had similar protein contents, 46.2 and 45.8 percent, respectively. The objective was to study the effect of replacing fish-meal (10 percent dry-matter basis of the diet) with silage (Table 10). The main factor responsible for the reduction in growth was assumed to be the reduction in feed intake, possibly caused by the lower palatability of the diet. It was concluded that, on a dry-matter basis, silage could replace 75 percent of the fish-meal and that other protein-containing materials, such as small fish, crabs, silkworms and animal offal, might be similarly processed for use as animal feed. In this regard, the author has used final molasses to preserve land crabs, livestock offal and earthworms, all destined for feeding pigs. Finally, the use of fish silage in growing/finishing rations sometimes results in the pork having an "off flavour. However, this can be easily controlled by reducing or removing the silage from the ration 20 days prior to slaughter.


In Viet Nam, two groups of Kaki Campbell ducklings were first exposed to (partially fed) crushed shrimp-head silage at ten days of age (Table 3). Subsequently, from 21 to 70 days, either 50 or 75 percent of the protein supplement in the diet was replaced by shrimp-head silage. Growth performance is presented in Table 11. It was concluded that the silage material could replace 75 percent of the fish/ soybean meal protein supplement.

Although information is not yet available, the author is currently involved in a duck project related to freshwater aquaculture in Cuba, where the primary objective is to improve the quality of the ecosystem using the proven means of duck excreta (Woynarovich, 1976). The proposed duck feeding system is based on a restricted amount of 18 percent concentrate ration up to 21 days of age, followed by a low-protein, liquid fattening diet - a mixture of two parts B molasses to one part ground fish wastes by weight (air-dry basis).


Beef cattle. In Cuba, acid silage material was promoted as a substitute for fish-meal in cattle feedlot rations based on restricted amounts of protein supplement and forage and free-choice molasses-urea (Preston, 1969). The practice was to substitute 1 kg of silage for 0.25 kg of fish-meal in order to provide 162 g of crude protein. The animals were also fed free-choice molasses/3 percent urea and fresh forage at the rate of 3 kg/100 kg liveweight, or had daily access to pasture for four hours. Daily liveweight gains for animals between 150 and 375 kg under commercial feedlot systems ranged from 0.6 to 0.8 kg (V. Rodríguez, personal communication).

10 - Replacement of fish-meal with shrimp heads, blood and molasses silage in diet* for pigs - Remplacement de la farine de poisson par de l'ensilage composé de têtes de crevettes, de sang et de mélasse pour l'alimentation de porcs - Sustitución de la harina de pescado por ensilaje de cabezas de camarón, sangre y melaza para la dieta de los cerdos




(percentage dry matter)

Initial liveweight (kg)




Final liveweight (kg)




DM feed consumption (kg/day)




Average daily gain (g)




DM feed conversion




Source: AHRI, 1993.
*Basal diet (% DM): ground maize, 58%; rice grain, 20%; fried soybeans, 5%; soybean meal, 5%; fish-meal, 10%; minerals and vitamins, 2%.
DM = dry matter.

11 - Growth performance of Kaki Campbell ducks fed shrimp-head silagea in place of protein supplementb - Performances de croissance de canards Kaki Campbell recevant un ensilage de têtes de crevettes en remplacement d'un complément protéique - Resultados del crecimiento de patos Kaki Campbell alimentados con ensilaje de cabezas de camarón en sustitución del suplemento de proteínas



50% protein supplement replaced by silage

75% protein supplement replaced by silage










1 206

1 191

1 238


1 400

1 410

1 413

Source: AHRI, 1993.
1See Table 3.
2Mixture of fish-meal and soybean meal.

At present, acid fish silage has been replaced by by-catch or fish wastes preserved in final molasses. During the shrimp season, the trawlers often bring in between 8 and 12 tonnes of by-catch each day. After removing the larger crustaceans and fish by hand, the smaller and more homogenous material is simply mixed with molasses. If the average size of the by-catch is larger than normal, the material is chopped before being mixed with molasses. In either case, it is usually fed within seven to ten days.

Dairy cattle. In most tropical and subtropical countries, the quality of pastures and forage tends to deteriorate during the dry winter months. This is reflected by lower levels of digestibility and available crude protein and generally results in a seasonal milk-yield reduction. The data in Table 12 show how the addition of 1 kg of fish silage to the daily diet of milk cows during the winter months, December through February, maintained milk production at a level comparable to that obtained during the wet season.

Camels. In Morocco, fish silage blocks have been used to feed camels. The basal ration used per 100 kg of liveweight was 1.5 kg of barley and 0.5 kg of straw. When 0.5 kg of fish silage blocks was used to substitute an equal amount of barley for camels fed the basal ration, dry-matter digestibility and growth performance improved by 2 and 17 percent, respectively (IAV, 1994).

Sheep. Fish silage has been used successfully in rations for sheep in Morocco (IAV, 1994) and in Cuba (Penedo, Cisneros and Sosa, 1988). The data in Table 13 show how growth performance was improved by more than 24 percent when 200 g of molasses fish silage blocks and 300 g of barley replaced 500 g of commercial ration (dry-matter basis) in rations for fattening sheep. Carcass evaluations were performed, and fish silage had no effect on meat flavour or taste. When the same type of silage replaced barley in diets for ewes prior to weaning, there was an improvement in digestibility and a reduction in feed conversion.

In Cuba, 70 percent sun-dried filter-pressed mud from the sugar mills has been mixed with 30 percent fish silage to produce a dry, filter-pressed mud/fish silage protein supplement (FPM/FSPS) for use in concentrate rations for fattening sheep. The composition (percentage dry matter) of the concentrate was: FPM/FSPS, 20 percent; bagasse pith/molasses/urea, 20 percent; sun-dried filter mud, 10 percent; final molasses, 5 percent; raw sugar, 38.45 percent; urea, 3.05 percent; mineral mixture, 2 percent; calcium sulphate, 1 percent; and salt, 0.5 percent. The feeding system comprised seven hours of poor pasture a day, free-choice, poor-quality hay and 2 kg of the concentrate. The authors reported that a total of 30 five-month-old sheep, of an average initial weight of 22.3 kg, gained 136 g/day during a 62-day trial using this feeding system (Penedo, Cisneros and Sosa, 1988).


It has been shown that by-catch or fish wastes, whole, chopped or ground, preserved in molasses or as fermented or acid silage, in the form of a paste or block, can replace more conventional sources of protein for pigs, ducks, sheep, cows, beef cattle and even camels!

The technology for the preparation offish silage exists. Its commercial application will depend on extension to producers and on its opportunity cost versus that of other conventional protein sources, as well as on the existence of other means of processing to meet environmental regulations.

12 - Use of acid fish silage to maintain milk production in the dry winter season in the subtropics - Utilisation d'ensilage acide de poisson pour maintenir la production laitière pendant la saison hivernale sèche en régions subtropicales - Uso de ensilaje de pescado ácido para mantener la producción de leche en la temporada seca de invierno en las regiones subtropicales

206 Holsteins

157 Holstein x zebus


Without fish silage

July 1975



August 1975



September 1975



With fish silage, 1 kg/day

December 1975



January 1976



February 1976



Source: Pérez (unpublished).

13 - Performance of sheep fed fish silage blocks* over 60 days - Performances de moutons recevant des blocs d'ensilage de poisson pendant 60 jours - Rendimiento de ovejas alimentadas con bloques de ensilaje de pescado durante 60 días

Control diet

Sunflower meal

Fish silage blocks

Fish silage blocks




Sunflower meal




Commercial ration (15% crude protein)








Dry-matter feed intake (g/day)




Average daily gain (g)




Source: IAV (in press).
*In addition to the above, all sheep received daily 300 g (dry matter) of straw and 10 g of a vitamin/mineral supplement.


AHRI. 1993. Report on the use of silage made of shrimp's head, blood and molasses as a protein supplement for pigs and ducks. Animal Husbandry Research Institute. 8 pp.

Alvarez, R.J. 1972. A comparative study of the nutritional value of the protein from ensiled fish. Cuban J. Agric. Sci., 6: 219-222.

Cameron, C.D.T. 1962. Acid fish offal silage as a source of protein in growing and finishing rations for bacon pigs. Can. J. Anim. Sci., 42: 41-42.

Cervantes, A. 1979. Ensilaje y harina de pescado en la ceba de cerdos. Informe de tema MINAG, La Habana, 75 pp.

Domínguez, P.L. 1988. Utilización de desperdicios alimentarios y de subproductos industriales agropecuarios y de la pesca en la alimentación del cerdo. En Alimentación porcina no convencional, CIDA, La Habana p. 7-69.

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