Tuesday, April 28, 2015

28/04/2015: EWOS: Annual Reports for 2014 published

On April 22, 2015, the Board of Directors of EWOS Group and EWOS Holding approved the financial statements for 2014. The financial statements are adjusted compared to the preliminary and unaudited 2014 results reported by EWOS Group and EWOS Holding on February 25, 2015. See HERE for details.
Image: Joshua Davis
The adjustments resulted in increased equity for EWOS Group and EWOS Holding by NOK 131.9 million as of December 31, 2014 and by NOK 129.3 million as of December 31, 2013 on a consolidated basis, and by NOK 144.8 million as of December 31, 2014 and by NOK 129.3 as of December 2013 for EWOS Holding AS on a stand-alone basis.    

There are no other changes in the financial statements.

Further details can be found in the Annual reports 2014 and Financial Statement release today published on the EWOS reporting portal

The next conference call will be held in connection with presentation of results for the 1st quarter 2015, on May 27th. Conference call details will be announced one week prior to the presentation.

Visit the EWOS site HERE.

The Aquaculturists
This blog is maintained by The Aquaculturists staff and is supported by the
magazine International Aquafeed which is published by
Perendale Publishers Ltd

For additional daily news from aquaculture around the world: aquaculture-news

Monday, April 27, 2015

27/04/2015: Immunostimulation in aquatic animals

by Philippe Tacon, Global Aquaculture Manager, Phileo

A survey made at the end of an aqua industry forum meeting in Vietnam last year has shown that for 63 percent of the participants, the most limiting challenge for developing aquaculture was health and disease management. Indeed, in recent years, we have seen numerous diseases appearing and impacting aquaculture production, such as WSSV and EMS in shrimp, or Infectious Salmon Anemia (ISA) in salmonids. Working around the classic Host-Pathogen-Environment triad, new technologies and management techniques have been developed to better control diseases in aquatic animals: vaccination, which has led to the decrease of antibiotic use in salmonids; biosecurity procedures in hatcheries and in farms; biofloc technology. All of these technologies have proven successful. Their further development and expanded use will certainly improve the way aquatic animals are farmed.

Another strategy is to increase the health of the animal through feeding, and this magazine might be a good place to discuss it. Well balanced diets can certainly improve the health status of a fish or a shrimp, but in some challenging conditions, like a pathogen infection, the use of immune stimulants can be required to enhance the response of the immune system.

When studying immune stimulation, it is important to understand that the immune system of aquatic animals differs not only between theirs and the mammalian one but also between teleost and crustacean. Fish are the first group in which a specific immune system appears in the evolutionary tree. The fish immune system therefore has a greatly inferior performance to that of mammals (see Tort et al 2003). It is less specific, less sensitive and has only oneclass of antibodies (IgM).

Fish being poikilothermic animals, it is highly dependent on temperature, low temperature slowing down the immune response up to 10 to 12 weeks. Fish rely by then more on their non-specific immune system (also called innate immunity) to fight against pathogens. The innate immune system recognises non-self molecules that could be of foreign origin - also called pathogen associated molecular patterns (PAMP) - and molecular patterns exposed though damage to the host. These patterns are recognised by germline-encoded pattern recognition receptors (PRR) or pattern recognition proteins (PRP). These molecular patterns can be for example peptidoglycans and lipopolysaccharides from bacteria cell walls, fungal b1, 3-glucan, viral double-stranded RNA and bacterial DNA (see Magnadottir 2006 for an overview of fish innate immunity). 

Fish innate immunity starts with first barrier defences such as mucus; it traps pathogens and includes lysozymes, antibacterial peptides which can eliminate pathogens. Neutrophils and macrophages are key cells of the innate immune complex  as they can phagocytose pathogens (a mechanism which is not temperature dependent) and release Reactive Oxygen species, which are toxic to pathogens. Completing this cellular response, the humoral response implicates the synthesis and release of antimicrobial components.

In shrimp, where the picture is even simpler as they rely only on innate immunity, we find the same type of mechanisms in place as in fish with phagocytosis performed by granulocytes (a specific form of the blood hemocyte cells) and humoral response. However the most effective mechanism of invertebrates (as arthropods) is cellular melanotic encapsulation. This requires the combination of circulating hemocytes and several associated proteins of the prophenoloxidase (proPO) activating system. Recognition of PAMPs such as LPS and β-1, 3 glucans by PRPs is an essential step for the activation of the proPO cascade (Amparyup et al 2013).

Stimulation of the innate immune system, which would enhance the speed and the effect of the immune response, is therefore possible by mimicking the effect of PAMP on PRR and PRP. In that regard, beta glucans have been studied for a long time in aquaculture and seem ‘the ideal’ immune stimulant in aquaculture (see Meena et al 2013 and Ringo et al 2012) as they can specifically activate macrophages in fish and the proPO cascade in shrimp.

Parietal fractions, such as Safmannan® are extracted from a selected Saccharomyces cerevisiae strain respecting strict EU manufacturing control standards. They contain beta glucans, mannan oligosaccharides that are all activators of the immune system (Song et al 2014).

Earlier internal trials have shown that yeast cell walls and parietal fractions have different effects in mycotoxin binding and immunity in aquatic animals. Indeed several trials done at the Hellenic Center for Marine Research in Greece have shown that yeast fraction products with similar manna/glucan ratios from Phileo, Lesaffre Animal Care Business Unit, have very different effects in the stimulation of immune parameters and in survival following challenge in Vibrio anguillarum.

It looks like not only the mannan and glucan content is of importance, but the strain and the drying processes are also key parameters to ensure a good effect in aquatic animals. Another concept that came out of these trials was that there is a threshold of yeast material to be ingested before it starts to kick in and improve the immune system. Product origin, quality, dosages and duration of treatment are all clearly linked.

A trial has been undertaken to further study a dose response of Safmannan® in a marine species. The objective was twofold: investigate the influence of parietal fractions in diets with a reduced amount of fishmeal, and determine the dosage needed for an optimum immune response (Yu et al 2014).

Six diets were designed (see table 1): a high fishmeal diet with 38.5 percent fish meal inclusion and no soybean meal (HFM) and 5 diets with 25 percent fishmeal and 20 percent soybean meal. These diets were supplemented with 0 (SBM), 250, 500, 1000 and 2000 g/T of Safmannan®. Juvenile Japanese seabass (18 g) were selected and distributed into 280 L tanks after 24 h starvation with 30 fish per tank, and six tanks per treatment. The water temperature was maintained. Fish were fed to apparent satiation twice daily at 08:00 and 15:00 for 72 days.

At the end of the treatment period fish were anesthetsed, weighed and viscera and blood were sampled. Intestine samples from the FM, Y0, Y4 and Y5 groups were removed from 2 fish in each replicate tank at the end of trial (12 fish per treatment) and processed for histology analysis (H & E staining). Morphological parameters associated with SBM-induced enteritis of anterior and distal intestines, including the height of mucosal folds (HMF), width of mucosal folds, lamina propria and connective tissue were quantified. 


After all samples were taken, 40 fish of each treatment (6–7 fish per tank) were divided into 2 groups and transferred into a still water system with temperature at 26 ± 1 °C. The fish were fed as before and recovered from weighing and sampling stress by a 2-week acclimation. Then they were challenged by intramuscular injection with Aeromonas veronii (CGMCC No. 4274) at 8 × 104 cells/100 g body weight. Ten fish from each tank were sampled for plasma immune parameters two days after challenge and the others (20 fish per treatment) were recorded for 7-day cumulative survival rate without any food.

This study showed a lower growth of SBM diets as expected compared to HFM diets, but an even lower growth with the 500g/T treatment, and a much better growth at 2000 g/T (Fig1). These results can be correlated to a wider width of mucosal folds in anterior and distal intestinal in SBM diets compared to HFM diets suggesting a negative effect of these diet on intestinal health, and also to a higher height of mucosal folds in the 2000 g/T group (Fig1). This suggests that Safmannan® at 2000 g/T was able to compensate the negative effect of soybean meal and increase gut health leading to a better growth.

The study also shows that IgM levels were significantly elevated after the bacterial challenge in the diet containing parietal fractions at 500g/T (Fig2) indicating a strong immune stimulation. The levels decrease as the yeast parietal fraction concentration is increased showing a potential fatigue of the immune system. This is confirmed by the survival of the fish after the challenge. The optimum dosage was 500g/T of Safmannan®, whereas higher dosage did not improve survival. Remarkably, we can see this optimum dosage for immune stimulation was also the one giving the lowest growth, confirming hypothesis that the strong stimulation of the immune system is at the expense of the growth potential of the fish.

This study highlights the duality of role of parietal fractions in fish depending on the dosage and feed composition: they can be used either as gut health enhancer (high dosage) or immune enhancer (low dosage).

Formulators and farmers can benefit from using this efficient and sustainable solution against pathogens but they need to choose quality products and work with proper (and proven) dosages and administration durations.

Read the magazine HERE.

The Aquaculturists
This blog is maintained by The Aquaculturists staff and is supported by the
magazine International Aquafeed which is published by
Perendale Publishers Ltd

For additional daily news from aquaculture around the world: aquaculture-news

Leiber company profile

Leiber has more than 140 employees. Each is a specialist in his or her domain. A well-proven team in a company following a clear strategy for more than 50 years: Working with values.

What makes us unique? We focus on what we know best. Yeast. Production on the highest level of quality. Latest technology. New findings from science and research. The performance of a team of specialists. This is what defines Leiber´s strategic orientation. This is what makes us truly entrepreneurial.

The markets´ requirements are changing - we are able to follow. This is how we became one of the leading manufacturers of specialised yeast products.

Visit the website HERE.

The Aquaculturists
This blog is maintained by The Aquaculturists staff and is supported by the
magazine International Aquafeed which is published by
Perendale Publishers Ltd

For additional daily news from aquaculture around the world: aquaculture-news

27/04/2015: Diabetes drug found in freshwater is a potential cause of intersex fish

A medication commonly taken for Type II diabetes, which is being found in freshwater systems worldwide, has been shown to cause intersex in fish –male fish that produce eggs, according to Newswise.

A study by Rebecca Klaper at the University of Wisconsin-Milwaukee determined exposure to the diabetes medicine metformin causes physical changes in male fish exposed to doses similar to the amount in wastewater effluent.

In addition to intersex conditions, fish exposed to metformin were smaller in size than those not exposed, said Klaper, a professor in UWM’s School of Freshwater Sciences.

The study, co-authored by Nicholas Niemuth, a researcher in Klaper’s lab, was recently published in the journal Chemosphere.

Photo: Sarah G
Because intersex fish are particularly prevalent downstream from wastewater treatment plants, many studies have investigated the effect of hormones from birth control pills, Klaper said.

Initially, the results of her study seemed surprising since metformin is not a hormone and it targets blood sugar regulation.

But Klaper said it is also prescribed to women with a common hormonal disease called polycystic ovary syndrome. The research in her lab indicates metformin could be a potential endocrine disruptor – a chemical that confuses the body’s complicated hormonal messaging system, interrupting a range of normal activities, including reproduction.

Of the chemicals she has detected in water samples collected from Lake Michigan, metformin stands out, Klaper said.

“It is the chemical we found in almost every sample and in the highest concentrations compared to other emerging contaminants – even higher than caffeine,” she said.

The prevalence of the chemical in samples led Klaper to investigate what effects the medication may have in the environment. In a previous study, she exposed mature fish to metformin, and although there were no physical changes, she found the genes related to hormones for egg production were being expressed in males as well as females – an indication of endocrine disruption.

For the current study, the researchers monitored fish that had continuous exposure to metformin from birth to adulthood. The next step is to determine the corresponding changes in the genome, which Klaper is doing at UWM’s Great Lakes Genomic Center.

“We’re now working on a paper that investigates the metabolic pathways at various points in the fishes’ life to see what is changing with exposure,” she says.

Visit the School of Freshwater Sciences site HERE.

The Aquaculturists
This blog is maintained by The Aquaculturists staff and is supported by the
magazine International Aquafeed which is published by
Perendale Publishers Ltd

For additional daily news from aquaculture around the world: aquaculture-news

27/04/2015: EWOS Innovation involved in new salmon research centre

The Norwegian Directorate of Fisheries has granted research permits to the Arctic Salmon Research Centre for the period 2015-2020. The research centre will give knowledge on fish farming in arctic environment in Finnmark, to optimize the ongoing operations and to explore the possibilities for growth in this region.

This centre will be important for the industry’s growth in Finnmark. This northernmost region in Norway has in many ways great conditions for fish farming, but we need more knowledge of the challenging conditions in Finnmark to get production results at the same level as fish farms further south, says a happy Olai Einen, research manager in Cermaq.


New knowledge on arctic conditions
For EWOS, it will be interesting to document new knowledge, together with Cermaq, in relation to fish farming in arctic conditions with lower sea temperatures and big differences in day-time length during the seasons. EWOS has, through research done by EWOS Innovation, good models for the significance of seasonal variations, and can adapt the salmon’s diet for different fish farming areas, says product manager Ernst M. Hevrøy.

To date, we have little systematic research activity on salmon farmed in Finnmark, and EWOS wants to be an important contributor to new, strategic knowledge when it comes to arctic salmon fish farming. In addition, it is important for EWOS to have access to research permits and research units in a very interesting salmon fish farming area.  That trials are done in full-scale fish farming conditions with a natural variation in environment, will give us an extra strength in this research cooperation. We are especially focused on the composition of the feed and its significance to the salmons growth, quality, wellbeing and health, says Ernst.

Unique challenges in the region
Salmon fish farming in Finnmark has had a weaker economic sustainability than fish farming further south. This is due to a longer production period, fish health challenges that are unique for the region, and a bigger variation in product quality.

Arctic Salmon Research Centre will find the causes to these challenges, by studying the significance of feed customized for the fish farming conditions in Finnmark. The trials will be done in full-scale with groups of spring smolt (S1), and autumn smolt (S0) that are kept from smolt to harvest. It has been given to research permits from now, and then two from the summer of 2016. The trials are planned to take place at Cermaqs existing facilities at Kirkneset, Kuvika and Segelsnes in the Hammerfest area.

The relevance of the results will be particularly high, as the trials are done at a practical fish farming scale, and under natural fish farming conditions in Finnmark, says Olai Eining.

The feed is the most important input in fish farming, and we do not know enough about what demands for feed the fish has, to be able to optimize fish farming in arctic areas, says Adel El-Mowafi, managing director of EWOS Innovation.

The arctic environmental conditions with variations in day-time length and low sea temperatures are the basis for the specific goals for the trial period 2015-2020:

  • Optimize growth and feed utilization in salmon by customize protein and energy in the feed to environmental conditions and growth pattern in Finnmark
  • Study the effect of feed with functional ingredients on sore prevention in salmon, and possibly contribute to healing of sores
  • Optimize fatty acids composition to maximize the utilization of essential oils EPA and DHA, and at the same time secure good health and quality in salmon from Finnmark.
  • Optimize pigment contents and antioxidants in feed to reduce problems with (at times) bad pigmentation and file quality
Planned start-up is in June 2015. Results will be shared through visits, lectures and publishing in scientific and popular science.

Visit the EWOS website HERE.

The Aquaculturists
This blog is maintained by The Aquaculturists staff and is supported by the
magazine International Aquafeed which is published by
Perendale Publishers Ltd

For additional daily news from aquaculture around the world: aquaculture-news

27/04/2015: French herring producers achieve MSC certification

http://www.msc.org/newsroom/news/french-herring-producers-achieve-msc-certificationFrench Herring Producers Association, FROM Nord, has achieved the Marine Stewardship Council (MSC) certification. As a result herring from this group can now be sold alongside the blue MSC ecolabel, indicating that the fish has been sustainably sourced.

The certification is recognition of the association’s good management and sustainable practices, and comes after a year of rigorous science-based assessment by independent auditors.
FROM Nord is a producers' association established in Boulogne-sur-Mer in 1965. It is made up of members from ocean-fishing companies at the ports of Boulogne-sur-Mer (EURONOR), Saint-Malo (Compagnie des Pêches Saint-Malo) and Fécamp (France Pélagique), artisan ships, trawlers, mussel dredgers and netters unloading at the ports of Dunkerque, Boulogne, Calais, Dieppe and Fécamp, as well as the Gulf of Gascogne.

Thierry Missonnier, Director of FROM Nord, expressed his delight at the certification: "We're extremely happy to now have confirmation from an independent third party of the sustainability of our management measures and the fishing practices of our members. This certification should also help us to better showcase herring production on the French and European market."

Herring is one of the most important species by volume for FROM Nord and for the region. The fishery landed more than 3,000 tonnes of herring in 2014 and has five artisan pelagic trawlers from the north-western part of France.

Edouard Le Bart, MSC Manager for France, explains that "The goal of the MSC is to make the market for seafood products more sustainable and give consumers the ability to actively participate in this global movement. However, this wouldn't be possible without the fishermen and organisations that commit to initiatives that showcase sustainable fishing. The producers association FROM Nord is already a driving force behind the certification of pollock, cod and haddock fisheries. I congratulate them for their commitment and their successful achievement of the certification for the herring fishery."

The certification of this fishery is expected to increase the availability of MSC labelled herring products on the market, with the majority of catches intended for processing, and the rest for the fresh market. According to a recent research amongst regular seafood buyers in France, 90% see marine conservation as a key issue with 45% actively seeking to buy sustainable seafood products*. 

* Research carried out by amr on behalf of MSC. Surveys took place between 19 March and 25 July 2014. More information can be found HERE

Visit the MSC website HERE.

The Aquaculturists
This blog is maintained by The Aquaculturists staff and is supported by the
magazine International Aquafeed which is published by
Perendale Publishers Ltd

For additional daily news from aquaculture around the world: aquaculture-news

Friday, April 24, 2015

24/04/2015: Wheat proteins: High quality proteins for aquaculture feeds

by Dr Emmanuelle Apper, MSc Aurélien Feneuil and Dr Frédérique Respondek, Tereos Innovation department

First published in International Aquafeed, March-April 2015 

Many fish feed producers now formulate low fishmeal diets. To ensure high growth performance, the use of high quality alternative protein is then required. Both Vital and Hydrolysed Wheat Gluten are high quality proteins. While they don’t exhibit the same behaviour at extrusion, they can both ensure good physical quality of pellets and high level of growth performance with high nitrogen and energy retention. 

Additionally, Vital and Hydrolysed Wheat Gluten may have some functional health benefits at gut level, especially by stimulating gut cell proliferation and antioxidative system without damaging gut structure. 
Intensive production of farmed fish fed with compound feeds has increased greatly, mainly due to the growth of aquaculture production, but also because it is the most efficient way of production (Olsen and Hasan, 2012). 

In such feeds, Fish Meal (FM) used to be the major source of proteins, especially for marine fish and salmonids (Tacon et al., 2011). Nevertheless, because of the limited amount of available FM on the market, its impact on the environment and marine diversity, and its increasing price, its utilisation has been progressively reduced in the formulation of diets. 

In order to achieve a low FM incorporation (below 10 percent in formula) without impairing growth performance, active research was conducted on plant proteins (PP), which represent an interesting alternative to FM. In this context, many studies were undertaken to evaluate the effects of replacing FM with different types of PP, tested one by one or in mixture, on fish growth and health. Among the tested PP being considered to replace FM, Wheat Proteins (WP), including Vital Wheat Gluten (VWG) and Hydrolysed Wheat Gluten (HWG) are easily available PP sources that have given very promising results from technological, nutritional and health points of view.

Vital and Hydrolysed Wheat Gluten exhibit different behaviour in extrusion and both proteins allow obtaining pellets of high physical quality
VWG has already been described elsewhere (Apper-Bossard et al., 2013) as an effective binder in fish feed, imparting good mechanical properties (i.e. durability and hardness) to the fish feed pellets as well as good water stability. Moreover, increased VWG inclusion rate in replacement of soy protein concentrate results in decreasing extruder motor load. Indeed, extrusion behaviour of 2 commercial salmon feed diets has been explored both at small scale (Application Centre, Tereos, Marckolsheim, France) and at a fish feed Technology Centre (scale-up; Nofima, Fana, Norway). 

One diet contained 10 percent VWG and the other 20 VWG. The two diets were extruded in the same processing conditions. This resulted in a lower motor load (i.e. torque) for 20 percent VWG compared to 10 percent VWG (36 percent versus 41 percent motor load). Higher inclusion of VWG in formulation leads to a decrease in motor load due to the lower water holding capacity of VWG compared to soy protein concentrate (Draganovic et al., 2011).

The technological properties of HWG had not yet been reported in the literature while VWG and HWG have different impacts on extruder system parameters, especially on motor load and pressure at the die. Indeed, replacing 25 percent of Crude Protein (CP) of a FM diet by either VWG or HWG (Voller et al., in preparation) results in lower motor load with HWG (283 and 376 Nm with HWG and VWG respectively).

The higher effect of VWG on the motor load can be attributed to the higher water holding capacity (table 1) of this ingredient (1.5 g of water/g) compared to HWG (0.6 g of water/g). The reduction in motor load can be seen as a direct process advantage allowing reduction of energy consumption during extrusion (Specific Mechanical Energy reduced from 65 to 50 Wh/kg). An alternative is to run the HWG diet at the same motor load as the VWG diet with the potential to increase the extrusion capacity.

Wheat Proteins: Amino acid profile
Wheat proteins are a source of functional amino acids, especially sulphur amino acids and leucine. They contain rather low levels of lysine, tryptophan, and arginine meaning that they should be complemented with these amino acids when used at high level in formulae. Several experiments showed WP can successfully replace a large part of FM when diets are supplemented with free lysine in salmonids (Davies et al., 1997). 

WPs contain a relatively high concentration of sulphur-containing amino acids, due to the numerous di-sulphur bonds (1.8 percent CP of methionine and 2.6 percent CP of cysteine), whereas PP sources are generally low in sulphur-containing amino acids. For instance, soybean meal and soy protein concentrate respectively contain 1.4 and 1.3 g/100 g CP of methionine and 1.3 and 1.4 g/100 g CP of cysteine. 

Furthermore, WPs are high in leucine, with about 7.9 g/100 g CP. Leucine is considered as the main amino acid triggering muscle protein synthesis and inhibiting proteolysis in mammals (Li et al., 2009) and probably in fish. Indeed, in different species, amino acids regulate the TOR signalling pathway (Seilliez et al., 2008). Furthermore, supplementing media containing 0.6 mM leucine with an additional 2.5 mM leucine reduced rates of protein degradation in rainbow trout primary myocytes by 8 percent (Cleveland, 2010). 


WPs are also rich in glutamine: from 35 to 40 percent CP. Glutamine is a major substrate for all rapidly proliferating cells and plays an important role in maintaining intestinal trophicity (Verlhac-Trichet, 2010). In addition, glutamine is one of the most important energy substrates of enterocytes. Free glutamine significantly increases enterocyte and microvilli length in catfish gut (Pohlenz et al., 2012), hybrid striped bass (Cheng et al., 2012), and juvenile hybrid sturgeon (Zhu et al., 2011). Glutamine also constitutes a major substrate for immune cells, thus modulating immune response (Verlhac-Trichet, 2010; Zhu et al., 2011; Cheng et al., 2012).

Moreover, glutamine plays a role in eliminating free radicals as it acts as a precursor for glutathione synthesis (Wu, 1998). Such effects are reported for juvenile hybrid sturgeon (Zhu et al., 2011) and hybrid striped bass (Cheng et al., 2012). Glutamine has proven to stimulate muscle synthesis in terrestrial vertebrates but such results are not available for fish. However, dietary glutamine supplementation increases growth performance in juvenile hybrid sturgeon (Qiyou et al., 2011) and in hybrid striped bass (Cheng et al., 2012).

Effects of wheat proteins on growth performance
Because of its high digestibility and its absence of anti-nutritional factors, replacement of a large proportion of FM with VWG results in similar growth performance and fish composition whatever the species are. The apparent CP digestibility of VWG is high, between 92 and 98.5 percent (Apper-Bossard et al., 2013). In rainbow trout, VWG successfully substitutes more than 50 percent FM providing diets supplemented with lysine without affecting protein and lipid composition of the carcasses (Davies et al., 1997). 

Furthermore, the inclusion of 14.5 percent VWG in diets does not adversely affect the flavour of fillets (Skonberg et al., 1998). In Atlantic salmon, the replacement of 35 percent FM with VWG without supplementing by lysine results in similar final body weight and growth (Storebakken et al., 2000). These authors estimate the replacement of FM with VWG without amino acid supplementation can go up to 50 percent based on the amount and the availability of lysine in VWG and on the requirement of fish. 

In European sea bass, substituting more than 50 percent FM with VWG does not impair palatability, growth performance, and nitrogen-energy retention (Tibaldi et al., 2003). In gilthead sea bream, the use of 88 percent CP from VWG not only successfully replaced FM but also produced better growth and feed conversion ratio, probably related to higher protein and energy intake of fish (Allan et al., 2000). In Nile tilapia fed with diets differing in their protein sources, the highest growth is reported for VWG, FM, and soybean extract diet. In shrimp, results are scarce but the replacement of up to 20 percent marine protein with VWG does not significantly affect feed efficiency and growth performance (Molina-Povida et al., 2004; Tereos internal data). 

HWG also seems promising in aquaculture feeds as it results in high growth performance. CP digestibility of HWG has recently been measured. It is very high and further increases with higher HWG inclusion rate in FM-diet for rainbow trout (figure 1; Apper et al., 2014). Recent studies on juvenile hybrid sturgeon show that the replacement of 1 to 5 percent of soy protein concentrate by 1 to 5 percent of HWG in a diet containing animal and plant proteins significantly increases growth performance (Qiyou, 2011). 

The use of 12.5 to 50 percent CP of HWG to replace high quality FM does not modify growth performance and feed efficiency in rainbow trout (Apper et al., 2014). In the same experiment, authors compared energy and nitrogen retention obtained with either VWG or HWG. Nitrogen retention was similar for the 2 protein sources, with very low metabolic losses of nitrogen (35.1 and 43.4 kg/ton of fish produced for HWG and VWG respectively). Energy retention was higher with HWG than with VWG.


Effects of wheat proteins on gut health and microbiota

Compared to a fishmeal-based diet, the use of Wheat Proteins does not damage gut morphology and microbiota. In Rainbow trout, the replacement of up to 50 percent high quality FM by either VWG or HWG results in no modification of gut structure (figures 2 and 3; Apper et al., 2014). Indeed, no areas of necrosis were observed in enterocytes, all appearing uniform, regular, and healthy. Microvilli observations confirmed such results, all microvilli being packed and showing the same density. Similarly, in the same study, microbiota was not significantly different between FM, HWG and VWG diets, with a predominance of Firmicutes.

Richness, OTUs, and diversity of microbiota were not different across treatments, suggesting that replacing up to 50 percent of high quality FM by WP is without consequence for gut health. Such results are typical of wheat proteins as soy-proteins or pea proteins have been demonstrated to impair gut morphology or microbiota at high inclusion rates (Mc Kellep Bakke et al., 2007; Penn et al., 2011).  

In soy-based diets, the inclusion of hydrolysed wheat proteins modulates gut function and morphology, the anti-oxidative system, and the non-specific immune system. The replacement from 1 to 5 percent of soy protein concentrate in a diet based on 20 percent FM, 20 percent soybean meal, eight percent corn gluten meal and 10 percent blood meal increased digestive enzyme activities and fold heights, modulated non-specific immune response and stimulated anti-oxidative status (Qiyou et al., 2011; Zhu et al., 2011). 

Interestingly, in these studies, the results of 3 percent of HWG inclusion were equivalent to results obtained when authors added one percent free glutamine in the soy protein concentrate diet. Such results suggest that HWG may have a bioactive role, by acting on highly proliferative cells or by saving energy as a glucose precursor. 

Due to their technological and nutritional properties, Vital and Hydrolysed Wheat Gluten already appear as high value protein sources for fish feeds. Furthermore, new insights on gut morphology, microbiota and health highlight a potential functional role of these proteins on the antioxidative system and on digestive enzyme activity and reveal that wheat proteins do not disturb carnivorous fish microbiota significantly. Further research is needed to confirm these functional benefits and to fully understand the underlying mechanisms.

Read the magazine HERE.

The Aquaculturists
This blog is maintained by The Aquaculturists staff and is supported by the
magazine International Aquafeed which is published by
Perendale Publishers Ltd

For additional daily news from aquaculture around the world: aquaculture-news