Tilapia is the name of a group of fishes belonging to the genera Oreochromis. Tilapia is, together with carp and salmon, one of the most important fish in aquaculture. Nile tilapia (Oreochromis niloticus) and Mozambique tilapia (Oreochromis mossambicus) are among the most known species.

Tilapia production

Tilapia is a relevant fish in aquaculture due to its rapid growth, large size and its high protein content. Other qualities include its omnivorous diet and its sustainable production.

Nile tilapia production was estimated by Food and Agriculture Organization (FAO) on 3.670.259 tons in 2014 (Chart 1). Tilapia is usually raised in tropical climates, as water temperature should not fall below 18áµ’C. Asia and Latin America are the major producing regions, being China its main producer, followed by Egypt and other Asian countries like Indonesia, Philippines and Thailand (Chart 2).

Major diseases in tilapia culture

Streptococcus is the most significant and pathogenic agent found in tilapia cultures worldwide, which usually appears in late stages (grow-out stage). Streptococcus agalactiae and Streptococcus iniae are the main strains causing disease. This infection results in generalized haemorrhagic septicaemia.

Meanwhile, Flavobacterium columnare commonly appears in early stages. Stressful conditions, like temperature fluctuations or poor water quality, favour the outbreak of the disease. This infection may be seen as white patches on the skin and fins that could later evolve into ulcers.

Other diseases include parasitical infections, such as Trichodina. Trichodina infest the gill and body surfaces, affecting breathing and chemical balance of the fish.

Iridovirus should be noted as the only currently documented viral disease present in tilapia, causing massive death in infected facilities (Chart 3).

Gut health relevance in aquaculture

The digestive system of fishes is the main entry point for pathogens, which may end in production losses. Thus, one of the key factors in aquaculture production is the maintenance of an adequate intestinal status and a stable gut microflora.

Several studies reveal that gastrointestinal microbiota plays an important role in nutrition and immunity of fishes, as gastrointestinal bacteria produce a wide range of enzymes that participate in digestion, but also help in the development and maturation of the gut immune system.

There are multiple sustainable approaches to work on a proper gut health, such as the use of probiotics, prebiotics, organic acids, yeast extracts, products based on cimenol ring or products rich in pronutrients.

Pronutrients are active molecules derived from plants, which induce the activation of genes related to cell physiology: pronutrients stimulate the production of tissue-specific proteins, which vary depending on the target cell of each pronutrient. This way, pronutrients optimize the functioning of the organs. They are classified into 10 groups depending on their target cell and function, and intestinal conditioners are the ones involved in enhancing gut function.

Intestinal conditioner pronutrients promote adequate renewal of the intestinal epithelium, improve the structure of the microvilli and strengthen tight junctions. These facts end in a greater absorption of nutrients, better integrity of the intestinal barrier and adequate production avoid pathogens attachment to the intestinal surface and facilitate their rapid elimination. In addition, a good intestinal status ensures a correct balance of the intestinal microflora.

Field trial: Effect of intestinal conditioner pronutrients on tilapia performance

In order to evaluate the use of intestinal conditioner pronutrients on productive performance in Nile tilapia fingerlings, a 12-week trial, between March and June of 2018, was performed at the facilities of Universidad Científica del Sur (Peru).

Fingerlings were reared in a water recycling system. Four different groups were stablished, and each group held four experimental units of 10 fishes per unit.  All groups were fed with a standard isoenergetic and isoproteic diet with different doses of the tested feed supplement, as seen below:

• Group T1: Control without pronutrients.
• Group T2: Intestinal conditioner pronutrients at 5 g/kg of feed.
• Group T3: Intestinal conditioner pronutrients at 10 g/kg of feed.
• Group T4: Intestinal conditioner pronutrients at 15 g/kg of feed.

Initial weight of studied tilapias was of 1 g and fingerlings were weighed every 15 days. Fish size was evaluated at the end of the trial.

Results in the chart below (Chart 4) show that all groups supplemented with intestinal conditioner pronutrients give rise to a greater growth and size of the fingerlings regarding the control group. However, the group with the best results is T3 (dosage of 10 g/kg of feed), which achieved a 16.7% higher weight than the control group, while T4 (15 g/kg of feed) obtained a 16.4% increase. T2, with the lowest inclusion rate (0.5 g/kg of feed) obtained better results than the control group, but this improvement was the smallest.

Regarding size (cm) of tilapia fingerlings, control group showed a greater variability in size, ranging from 6 to 14 cm, while batches treated with pronutrients were more uniform, with lengths ranging from 9 to 12 cm (Chart 5).

This trial revealed that diets with 10 g/kg of intestinal conditioner pronutrients in tilapia fingerlings helped to obtain a greater growth (+16%) and a more uniform sizes at 12 weeks of breeding. Both evaluated parameters showed that the use of intestinal conditioner pronutrients allows to reach the desired weight faster and with a better uniformity, so that raising tilapia is much easier and profitable.

Conclusions

Fast growth, together with other qualities, makes tilapia one of the most cultured fish worldwide. As the digestive system is the main entry point for pathogens, one key factor in aquaculture is to maintain gut health and microflora activity. The use of intestinal conditioner pronutrients helps on the aforementioned and allows an enhanced productive performance.