The Problem
The worldwide seafood catch is
declining because of over-fishing, pollution and expanding populations.
Although aquaculture now represents only a small percent of the combined total,
a leveling off of the supply of seafood together with the rising demand for fin
fish and crustaceans means that aquaculture is the growth industry of the
future. In this light, much emphasis has been placed on species selection,
adaptation, feeding, rearing, harvesting, equipment or on other physical
devices. But, little thought has been given to the accompanying aquatic
environment, other than to change the water.
Mother Nature just can’t cope with the overload in the oceans, let alone the accumulation of uneaten feed, excreta, etc. in a confined aquatic environment. Where the water can be changed, it must be cleaned more often. Where the water can’t be changed, the confined aquatic environment deteriorates and so do profits.
Mother Nature just can’t cope with the overload in the oceans, let alone the accumulation of uneaten feed, excreta, etc. in a confined aquatic environment. Where the water can be changed, it must be cleaned more often. Where the water can’t be changed, the confined aquatic environment deteriorates and so do profits.
Accumulation of uneaten feed and
excreta create a sludge on the bottom and turbid water above. Digestion by
indigenous microorganisms is slow and takes dissolved oxygen away from the
crop. In addition, there is a build-up of ammonia, nitrites and other toxic or
inhibitory products. Therefore, to improve the aquatic environment, there must
be a reduction in accumulation of these substances. It is evident that these
problems will not go away on their own. Also, it is evident that chemical and
physical methods are costly and are only temporarily beneficial. To that
end, what can be done that is both safe and cost effective?
The
Solution
The best point of attack is to
reduce the accumulation of sludge. This is done by bioaugmentation of the
existing microorganisms through regular addition of biological active seed
cultures such as ESS Microbes on a regular preventive maintenance schedule.
Bioaugmentation means helping Mother Nature do a better job microbiologically
by supplementing the indigenous microflora. This is in contrast to the
continued use of chemicals or increasing the frequency of water change, if, in
fact, the water can be changed at all. Just like aspirin relieves some cold
symptoms but does not cure the cold, chemical additives or water changes
temporarily relieve the symptoms of the poor aquatic environment, but do not
cure the problem.
Biologically
Active Seed Cultures
Nature abounds with microbial
cultures in the air, soil and water. These microflora exist because they have
adapted and continue to adapt to changes in the environment. They have adapted
because they can metabolize certain surrounding substances to obtain energy and
nutrients. But, this does not mean they can handle an ever-increasing load.
An aquatic environment with few fish
or crustaceans would probably clean itself over time. However, such a system
would not feed many people or make a profit for the grower. Intensive
aquaculture involves many fish or crustaceans and as many cycles as possible
during a season. Accordingly, the aquatic environment is not able to clean
itself under these circumstances, and limits have been reached in many places
as to water changes and the benefits of more chemical additives.
Mortality and poor or abnormal
growth are symptoms of a bad aquatic environment. If the aquatic environment is
improved, the symptoms will disappear because the cause has been eliminated.
How can this be done?
The answer is bioaugmentation by
regular additions of ESS Microbes which contains several strains of
naturally-occurring microorganisms that have been isolated and trained to
produce large amounts of digestive enzymes when introduced into an aquatic
environment. This on the job training has been done to the extent that these
biologically active seed cultures are strains which are 1000 times more active
than those found in nature. By adding on a regular basis, these more efficient
cultures establish themselves and maintain dominance over those less efficient
already present.
Nitrification
and Denitrification
Nitrification is a two-step process
than involves two groups of microorganisms. The first step is oxidation of
ammonia to nitrite. Nitrosomonas is the most common genus involved in this
reaction. The most common genus involved in the second stage, oxidation of
nitrite to nitrate, is Nitrobacter. Both of these genera are autotrophic and
subject to dissolved oxygen (DO) and biological oxygen demand (BOD) limits.
They are very fastidious in growth habits and attempts to culture them
commercially have met with little success. Although ESS Microbes does not
contain either, the product enhances the natural action by creating a more favorable
environment, particularly by reducing the BOD. In addition, ammonia may be
oxidized directly to nitrogen gas. In any event, the ammonia levels are
reduced.
Several heterotrophic bacteria that
aerobically oxidize organic matter can also reduce nitrites and nitrates and
thus function as facultative denitrifiers. Among these are members or the genus
Bacillus. ESS Microbes contains four species of this genus and the product
functions as a facultative denitrifier as evidenced by university results which
showed reductions in accumulation of nitrites and nitrates. Under low DO, the
oxygen in nitrites and nitrates is utilized. However, as stated above reduction
in nitrites and nitrates may be because of reduced ammonia accumulation.
The autotrophic denitrifiers do not
function when the DO is above a critical level of 0.1 to 0.2 mg./L. A DO
similar to this or slightly higher than that for the autotrophs will also
inhibit activity of the facultative denitrifiers. If enough DO is available,
this will be used in preference to the oxygen in nitrites and nitrates.
Presence of carbonaceous matter
(sludge such as accumulated excreta, uneaten feed, etc.) will inhibit
denitrification by the autotrophs. This does not influence the facultative
microorganisms. ESS Microbes reduces sludge generation and accumulation as
shown by its use in waste treatment plants and by university data. ESS Microbes
is a special formulation of ESS Microbes designed for use in saltwater
aquaculture systems.
Summary
ESS Microbes does not contain
Nitrosomonas or Nitrobacter. However, not only does this product function as a
facultative denitrifier, it also creates a more favorable environment for the
autotrophs by reducing the BOD. In addition, ESS Microbes may oxidize or
otherwise utilize ammonia directly.
Enzymes
for sustainable aquaculture
Story by: N. Felix and S. Selvaraj,
Department of Aquaculture, Fisheries College and Research Institute,
Thoothukkudi-628008, Tamilnadu, India
The expansion of global aquaculture production is increasing the demand for aquaculture feeds. Fishmeal is the main and most critical ingredient in aquafeed production. The increasing cost of fishmeal has encouraged feed manufacturers search for cheaper alternative protein sources such as plant proteins. Though the palatability of many plant materials has demerits, anti-nutritional factors are the most serious concern in replacing the fishmeal completely in feed formulations. Anti-nutritional factors have an adverse impact on the digestion of feed and its efficiency. There are many kinds of anti-nutritional factors. Three that are associated with the most widely used plant materials are trypsin inhibitor proteins, glucosinolates and phytate. Heat inactivation and water soaking are the two common detoxification methods used to overcome most of the anti-nutritional factors.
Enzymes provide additional powerful tools that can inactivate anti-nutritional factors and enhance the nutritional value of plant-based protein in feeds. They provide a natural way to transform complex feed components into absorbable nutrients. Endogenous enzymes found in the fishes digestive system help to break down large organic molecules like starch, cellulose and protein into simpler substances. The addition of enzymes in feed can improve nutrient utilization reducing feed cost and the excretion of nutrients into the environment.
Phytic acid is one of the most powerful anti-nutritional factors in plant ingredients. The anti-nutritional activity of phytic acid can be eliminated by the addition of relevant enzymes, for example phytase. The phytic acid or phytate found in cereals, legume grains and oil seeds is bound with phosphorus and also with calcium and magnesium, trace elements like iron and zinc, protein and amino acids. Most fishes do not possess their own enzymes to break down the phytate and release the nutrients so they pass through the fish undigested. This is why higher proportions of valuable nutrients from vegetable sources are not utilized by the animals and are wasted as excreta. The feed enzyme phytase not only releases phosphorus from the phytate but also releases minerals and amino acids that are also bound, paving the way for maximum utilization of nutrients.
Advantages of phytase
1. Since the phosphorus bound in phytate becomes available as nutrient due to the addition of phytase, the inclusion of inorganic phosphorus such as fishmeal can be drastically reduced.
2. The environmental performance of aquaculture operations is under scrutiny due to the discharge of nutrients into the surrounding ecosystems. Excessive phosphorus in particular is an important factor in the eutrophication of waterways. Phosporus bound in phytate may be unavailable to the fish but it will still ultimately be released into the environment as microbial action breaks down the fishes waste. The addition of phytase reduces the release of nutrients into the environment by making the bound phosphorus available to the fish for growth – so it is incorporated into the fishes body instead.
3. Phytase added to the diets improves protein and amino acid digestion in fishes.
4. Phytase can improve the metabolisable energy of feeds by breaking down the phytate-lipid complex.
5. Cheaper plant based protein sources can be substituted for fishmeal lowering feed costs.
Non – starch polysaccharides (NSP)
Another important anti-nutritional factor that can be addressed with feed enzymes is non-starch polysaccharides (NSP), present in the plant materials and found to reduce the performance of animals. Their anti-nutritive effects are mainly due to the increased viscosity of the digest in the intestine and the enclosure of nutrients making them unavailable to digestion. Since the animals lack the intestinal enzymes for the degradation of non-starch polysaccharides, the supplementation of degrading enzymes in the diet will break down these anti-nutritive factors and result in better feed utilization. Such an approach has been successfully used in poultry diets.
Experimental results using feed enzymes
A number of studies have reported successful use of enzymes to combat anti-nutritional factors in plant proteins for fish feeds. Phytase added diets have been shown to have a higher feed intake, growth and better food conversion efficiency than control diets in Channel catfish, as well as reduced phosphorus load in their faecal matter1. Trout fed with phytase-incorporated soybean based diets have been reported to show a 22% improvement over control fish as phosphorus availability increased from 46% to over 70%2. Microbial phytase added diets containing a higher proportion of plant protein have been shown to improve phosphorus and protein digestibility in Atlantic salmon3.
A feeding trial conducted with tilapia Oreochromisniloticus fingerlings in Brazil showed the significance of phytase in plant protein based diets. The feed was supplemented with commercial phytase enzyme “Natuphas??? at 0, 500, 1500 and 3000 units per kilogram of feed. Fishes fed with 500 units of Natuphas showed higher weight gain and a better food conversion ratio of 1.80. Supplementation of protease-based additive equaled the performance of low protein milk fish diet (24% protein) up to the level of higher protein diets (28% protein)5.
The addition of commercial enzyme Phytase in soybean based diets free of fish meal showed equal performance of diets containing 10 or 12% fish meal in carp and tilapia4,5,6.
The future
Aquaculture is fast growing Industry. Successful and sustainable aquaculture depends on economically viable and environmental friendly feeds. Feed is the major operational cost involving 50 to 60% of the total cost in intensive farming. The major feed ingredient, fishmeal, is expensive and there is increasing competition with other livestock industries for the available supply. Hence, research work has been focussed to find alternatives to fishmeal. One alternative is to substitute fishmeal with plant proteins supplemented with feed enzymes. Phytase enzyme is able to release the phosphorus bound in phytate and this permits feed manufacturers to reduce the fishmeal and lower the cost of feed production. Improved phosphorus utilization can also help reduce the discharge of nutrients into the environment. Enzymes can therefore play an important role in formulating eco-friendly aquafeeds. Currently, the use of enzymes is able to reduce fishmeal inclusion by around 5% in most aquafeeds with potential for more as techniques are refined. This may help to reduce the demand for fishmeal from the aquaculture sector in coming years.
Proteases
Incorporating Proteases in diets
helps reduce feed costs without compromising performance.
Protein is one of the most expensive
components of any livestock diet, but is essential for growth. The challenge, therefore,
is to use protein as efficiently as possible so as to reduce feed costs without
compromising animal health.
Proteases are enzymes that break
down protein molecules into the amino acids and peptides needed by animals.
Your
benefits
Adding Proteases can:
·
Increase protein digestibility
·
Improve protein utilization by the
animal
·
Allow lower quality protein sources
to be included in diets
·
Protect the environment by reducing
the nitrogen excretion from animal husbandry
Specifically developed for inclusion
in animal diets, Proteases significantly increases the digestibility of
protein.
It complements naturally occurring
proteases in feed, and considerably increases amino acid and peptide supply so
as to enhance animal performance. It improves the digestibility of a wide range
of protein sources and cereals, allowing savings in diet costs.
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