Aquaculture production on the African continent has increased in recent years, with annual growth of 15.55%, with Egypt, Nigeria, Uganda and Ghana being the main producing countries.

The African catfish or Clarias gariepinus is one of the main aquaculture species produced, due to its a highly resistant and productive specie. As in other aquaculture species, feed digestibility problems are common in catfish, especially during the transition phase from endogenous to exogenous feeding, because of the incomplete development of the digestive tract of the larvae.

These digestibility problems are associated with the use of plant protein sources in the manufacture of aquaculture feed and the presence of stressors capable of disturbing gut health.

Intestinal conditioner pronutrients are a natural solution, as they improve the gut health, favoring the digestibility of feed and the absorption of nutrients. Pronutrients are active molecules of botanical origin, which act enhancing the integrity of the intestinal epithelium.

These intestinal conditioner pronutrients are marketed under the name Alquernat Nebsui, a product developed and patented by Biovet S.A.

Catfish production in Nigeria

Production of African catfish (C. gariepinus) began in Nigeria in the 1970s, however, it was not until 1980s, that the production of this aquaculture species significantly increased thanks to the development of artificial reproduction methods.

Nigeria is the second country with the highest aquaculture production on the African continent, with catfish being the most produced species with a production of 160,000 tons in 2015.

The profitability of this species is due, on the one hand, to its high resistance to adverse environmental conditions and its productivity since they reach the commercial weight (1.5kg) in just over half a year. On the other hand, its meat is highly appreciated, for its consistency and white color, which is reflected in a high commercial , value, for example, in the case of Nigeria the commercial price of meat is around 700 naira/kg, which correspond to 1.95 euros/kg.

Problems related to feeding on African catfish

Availability of raw materials and feed

In the African continent there has been a sharp change in the type of aquaculture production, changing from a mainly extensive production, which did not require a specific feed, to semi-intesive or intensive production, where feed is one of the main productive factors. The establishment of intensive production is associated with the need to provide specific feed for animals, with a high protein content, to achieve a high productive performance.

In Nigeria, the number of companies intended for the specific production of aquaculture feed is small, so there is a marked dependence on the importation of both raw materials and feed.

This dependence causes large price fluctuations, difficult for producers to bear, considering that feed accounts for between 75-80% of the total production cost. Ensuring that feed supplied to animals is properly digested and absorbed is essential to ensure farms viability.

Use of plant protein sources for feed manufacturing

Like other aquaculture species, siluriform require a high percentage of protein in the diet. In the case of African catfish (C. gariepinus) the protein requirement is 37%. To cover these high levels of protein in the diet, a high percentage of fishmeal was initially included in the feed.

Currently there is a growing tendency to replace the use of fishmeal with sources of plant protein. However, the use of plant-based proteins brings with it some drawbacks. On the one hand, plant-based protein contains anti-nutritional factors that reduce the activity of digestive enzymes. These factors are present in different proportions depending on the plant and can significantly reduce feed digestibility.

On the other hand, the amino acidic profile of these protein sources does not always meet the specific needs of the species. In the case of catfish, the most limiting amino acid is lysine.

Stressors in intensive fish farming

In intensive aquaculture farming animals are exposed to a lot of stressors that affect their gut health. Stressors include high breeding densities, manipulations associated with vaccination, weighing and transport of animals, as well as water quality.

All these factors cause chronic stress in animals, resulting immunosuppression, especially relevant at the digestive level. The affectation of the immune system of animals promotes colonization of the digestive tract by different pathogenic microorganisms, increasing the prevalence of diseases.

Feeding during the larval phase

When growing larvae, the transition from endogenous to exogenous feeding is a critical step, in which high mortality can take place, if the development of the gut with the growing processes is not properly synchronized. In the case of African catfish, exogenous feeding begins at 4 days after hatching (DAH) and a mixed feeding (endogenous and exogenous) is performed until full reabsorption of the yolk, which takes place at 7 DAH. This mixed feeding phase is especially critical as the digestive tract is in the early stages of its development.

The digestive tract in African catfish is not fully developed until the 324 DAH. To ensure the viability of the larvae it is essential to ensure that they are able to digest the first feed supplied. The administration of intestinal conditioner pronutrients, allows to ensure the development of the digestive tract and improve intestinal integrity during this first stage, increasing the digestibility of the initial feed.

Natural solution – intestinal conditioner pronutrients to improve gut health

In order to ensure intestinal health in aquaculture species, improve feed digestibility and, therefore, economic profitability, from Biovet S.A. we have developed and patented a natural product based on intestinal conditioner pronutrients.

Intestinal conditioner pronutrients are active molecules of botanical origin, derived from shikimic acid, that act at the metagenetic level increasing the synthesis of functional proteins in enterocytes. The addition of these active molecules in feed, increase the renewal of enterocytes, improving intestinal integrity.

At the same time, in vitro studies have shown that the use of intestinal conditioner pronutrients improves the tight junctions between enterocytes, which helps prevent colonization of the intestinal epithelium by pathogenic microorganisms.

Intestinal conditioner pronutrients improve the absorption of nutrients (vitamins, amino acids, minerals, etc.) at the intestinal level, improving animal growth and feed use.

Studies in tilapia fingerlings, confirm that the use of intestinal conditioner pronutrients improves intestinal health, increasing production parameters. The use of these pronutrients allows to improve the weight of animals by 16.7%.

Therefore, intestinal conditioner pronutrients represent a promising solution to the main problems mentioned in the previous paragraphs, since:

• They improve the use of feed – higher productive performance of the feed, higher economic profitability of the farm.
• Improve digestibility and intestinal integrity – reducing the negative effects of antinutritional factors and increasing the digestibility of plant-based protein.
• Improved gut health – increased stress tolerance and lower prevalence of digestive diseases
• Improved development of the digestive system in larvae and fry – greater adaptation to diets.

Conclusion

African catfish (C. gariepinus) is one of the main aquaculture species cultivated on the African continent, due to its productive aptitude and high market value.

In the intensive production of catfish, as in other aquaculture productions, the cost of feed is particularly relevant. This is particularly relevant on the African continent, where the availability of raw materials and feed depends heavily on external markets, with consequent fluctuations in prices.

At the same time, it should be noted that there are various factors such as the use of plant protein sources in feed manufacturing or the stress to which animals are subjected, that can affect their intestinal health. This is especially important during larval development, as their digestive tract is not fully developed.

The use of intestinal conditioner pronutrients improves gut health and intestinal integrity, reducing the impact of these limitations and therefore, improving feed utilization and increasing the weight of animals by up to 16.7%.

Intestinal conditioner pronutrients are marketed under the name Alquernat Nebsui from Biovet S.A.

Bibliography

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