The world population increases daily and is estimated to reach 8,24 billion people in 2030 [1,2]. Consequently, the supply of safe and affordable food may become a big challenge for the market. Fish is one of the great sources of protein and omega 3 for the population . According to FAO , 67% of all fish consumed comes from aquaculture, and the Nile tilapia is the second most cultivated fish species in the world and the first in Brazil .
For tilapia production to continue on the rise, it is essential to utilize feeds with high-quality ingredients, with adequate levels of nutrients (proteins, fats, vitamins and minerals) that can guarantee its nutritional condition, thus preserving the animal's health, productivity levels and performance, while also providing greater profitability for producers.
Choosing the right ingredients when formulating for animal nutrition is a primary task for the zootechnician and/or the professional responsible for the formulation. Nowadays, several highly technological ingredients are available in the market for the production of tilapia feeds. By choosing ingredients that have high digestibility indices, the formulators increase the efficiency of the feed, providing the correct nutrition and maintaining animal health.
Protein hydrolysates, such as Chicken Protein Hydrolysate (CPH), Chicken Liver Protein Hydrolysate (CLPH) and Feather Protein Hydrolysate (FPH), have highly digestible amino acids — according to digestibility coefficients determined by dos Santos Cardoso et al. (2021)  and the use of these ingredients can increase the performance of tilapia feeds.
Feed is defined as food provided to animals, either domestic or production animals, for nutritional maintenance. Production animals, such as tilapia, need to consume a high-performance feed to reach their productive potential. Food corresponds to 60 to 70% of animal production costs. Accordingly, one should also be aware of the benefits it offers to the animal — from the most basic needs to performance and health gains, such as an improvement in the immune system and an increase in fillet yield.
Feed and animal health in tilapicultura
To optimize the area of production, tilapia is cultivated in intensive systems, with a high density of animals per cubic meter of the excavated tanks and cages. Therefore, attention must be paid to the level of stress in relation to feeding aspects, impacting the animals' health and, consequently, the decrease in production, since this factor reflects directly on zootechnical indexes such as feed conversion, weight gain, and survival .
In feed formulation, relevant factors, such as feeding habits and species nutritional requirements, must be considered in order to obtain the best product for each stage of cultivation (larva, fingerling and fattening), since each phase demands specific nutrients.
One of these concepts is feed digestibility, which is directly linked to nutrient absorption, health, growth and development of animals. In addition, within aquaculture, low digestibility can also interfere with the quality of the body of water, since the excreted residues accumulate in the rearing environment, providing the growth of undesirable organisms (such as bacteria) and increasing the concentration of toxic substances such as ammonia, nitrites and nitrates, which decrease the health of the animals.
Adequate protein levels in the formulation provide great benefits because, besides protecting the water body where the fish are inserted, it favors the proper functioning of these animals' organisms. This is possible because these proteins are directly related to muscle growth, as well as the formation of oxygen-transporting molecules, hormones and protection against pathogenic organisms.
Another relevant aspect to evaluate (other than levels of protein, fat, vitamins, macro and micro minerals that make up the feed) is whether the food provides protective conditions at a molecular level — such as antioxidant components, since the presence of free radicals in large quantities causes great harm to the health of animals.
Functional ingredients for tilapia feed formulation
With an increasingly competitive market, the producer must dispose of several tools in order to stand out and sustain profitability. The tilapiculturist is no different from other producers — they also have to make use of various resources to grow tilapia at the lowest costs and achieve greater profit, while maintaining a feed with high-level quality.
Feeds formulated with components developed through advanced technological processes can provide greater nutrient availability to the animal. BRF Ingredients  produces and distributes several high-technology ingredients — among them, protein hydrolysates.
Producing protein hydrolysates through the enzymatic hydrolysis process modifies the raw material and improves its nutritional value, developing a product with high protein quality . This hydrolysis enables the production of free amino acids and smaller chain bioactive peptides of smaller chains — that is, with low molecular weight.
As reported in a scientific article published in the Journal of Animal Science and Biotechnology , these bioactive peptides positively act upon the animals' immune systems. This happens because these molecules deliver various actions — such as antioxidant and anti-inflammatory activities, regulation of visceral fat deposition, and others.
In the following paragraphs, we will discuss some of the main functional ingredients, with high protein content, that can be incorporated into tilapia feeds with the function of improving zootechnical performance.
When producing hydrolyzed proteins, one of the most relevant parameters to consider is the protein source, since the nature and quality of the raw material used can impact the hydrolysis reaction, the quality and the functionality of the final product.
The main sources of raw material to produce hydrolyzed proteins are the eviscerations of swine and poultry. They generate products such as Chicken Protein Hydrolysate (CPH), Feather Protein Hydrolysate (FPH) and Hydrolyzed Porcine Mucosa Protein (HPMP).
Chicken Protein Hydrolysate
Chicken Protein Hydrolysate is made from viscera, offal and chicken meat. The enzymatic hydrolysis process is used to prepare this ingredient. It breaks the amino acids and peptides into smaller chains, with low molecular weight (100% below 3000Da), allowing easy absorption by the animal's digestive system.
According to a study conducted by dos Santos Cardoso et. al (2020) , this product has a high protein content, above 75%, and a balanced amino acid profile — which translates that all the essential amino acids are present in high amounts. CPH even provides high in vivo digestibility, while being highly palatable for Nile Tilapia .
A study conducted by Carvalho et. al (2020) , at Universidade Estadual do Oeste do Paraná, which analyzed the performance of animals fed control diets and animals fed diets enriched with Chicken Protein Hydrolysate, found that including CPH in the diet improves the zootechnical indexes of juvenile Nile tilapia — with emphasis on size and weight (see reference values of the study), when compared to the diet without the addition of the ingredient.
Feather Protein Hydrolysate
Chicken feathers contain high crude protein content. However, this protein is in the form of keratin — a substance difficult to digest. So, to improve its digestion, it can undergo a physical-chemical steam treatment for partial hydrolysis of keratin. However, this process causes the nutritional loss of essential amino acids such as methionine, lysine and tryptophan. To improve the use of this protein, it can go through an enzymatic hydrolysis process — a procedure done under milder pH and temperature conditions. In this way, it is possible to release amino acids and small peptides without molecular modification.
In the process of hydrolysis by proteolytic enzymes, the breaking of the peptide bond is independent of the substrate's peptide chain size, thus breaking the peptide bonds of the terminal amino acids.
Feather Protein Hydrolysate is a product with high protein content, presenting a minimum of 750 g kg-1 of protein to dry matter. It is characterized by the presence of all essential amino acids in considerable amounts — especially the amino acids leucine, phenylamine and tryptophan .
Hydrolyzed Porcine Mucosa Protein
The high productivity of pigs has brought a great challenge for the adequate destination of the evisceration co-products.
The quality of a protein product is measured based by its amino acid profile, which makes it possible to provide standardized amino acid for protein metabolism in animal cells, as calculated by the growth of the animal .
In this sense, Hydrolyzed Porcine Mucosa Protein fits perfectly, as it has an excellent amino acid profile, with the advantage that the hydrolysis process provides — the production of low molecular weight peptides, which may present bioactivity features. There are also improvements in the zootechnical indexes and the high palatability is another feature worthy of mention.
For a formulated feed to reach a higher potential, most importantly it must deliver results — especially in the nutrition, development and health of the animals. Therefore, choosing ingredients of excellent quality is essential.
In a scenario of high competitiveness, investing in the production of highly balanced feed, with highly digestible ingredients and also with palatability association, allows to achieve the desired goals of increased production and profitability.
Another essential factor is to always keep up to date with technological innovations in the animal nutrition market — this permits making substitutions that add nutritional value to the feed and reduce production costs.
Choosing the right ingredients or ingredients with the most suitable features for each species directly impacts the results, whether in terms of the animal's health or terms of zootechnical indexes — such as size and weight. Therefore, comparing the advantages and disadvantages of all available alternatives is essential to obtain the best results.
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