Probiotics vs. Enzymes: Understanding Your Aquaculture Products
We believe the future of aquaculture nutrition, disease management, and environmental treatment is biological. At QB Labs, we’re constantly looking at the effects of various microorganisms to replace antibiotics, augment natural fish/shrimp biological processes, and improve environmental impacts of commercial aquaculture. While educating customers on our products, we’re often asked the question: “what’s the difference between a probiotic and an enzyme?” So, we decided to put together a quick overview of the two: what they are, how they’re related, and when each should be used in aquaculture The Background: Why are we using microorganisms in aquaculture? In recent years, advanced DNA and molecular analyses have enabled a more detailed study of the gut microbiome and its importance in food metabolism and proper nutrient absorption. The knowledge we have gathered so far has forever changed our view of human and animal nutrition. This newfound understanding of the relationship between different species has revolutionized nutrition science and shifted the focus in aquaculture from making the best “cocktail” of proteins and oils to more advanced and sophisticated feed additives. This advanced development of feed additives in aquaculture is mostly focused on enzymes and beneficial bacteria (often called “probiotics”) due to their promising qualities in terms of economic and environmental sustainability, as well as their connection to existing natural processes in the fish/shrimp being cultivated. But beneficial bacteria (probiotics) are not the same as enzymes. To understand the differences between them, and choose the optimal ingredients for nutrition and environmental treatment, we need to better understand what these substances actually are. Enzymes Enzymes are proteins produced by living organisms which act as catalysts in specific biochemical reactions. They speed up the chemical reaction by lowering the amount of energy that is necessary for the reaction to begin. In these reactions, the enzyme first binds one or more reactant molecules (depending on its specific mode of action), positioning them in the right orientation to react and break specific molecular bonds to create final products. Enzymes are essential components of any living organism – without their intervention, life couldn’t exist as we know it. Enzymes often used in aquaculture include protease, amylase, lipase, esterase, cellulase, xylanase and urease. They are used because they can increase the availability of nutrients, improve nutrient absorption in the digestive system, and drive faster fish growth rates. Some enzymes, for example proteases, can indirectly aid nutrition and health of farmed fish by reacting with built-up waste materials in the pond water. Protease is thus used for purifying the pond water and creating a healthier environment for the development of aquatic animals. Figure 1. https://www.sciencelearn.org.nz/resources/1840-digestive-enzymes In aquaculture, the primary purpose of feed enzymes is to improve digestion. This is especially important in early stages of development, considering that some fish larvae lack certain important enzymes, leading to nutrient deficiency. A lack of certain enzymes has also been observed in some mature fish/shrimp, which is why feed enzymes can be beneficial for all stages of growth. How do enzymes aid digestion?
- Phosphorus optimization – Phosphorus is an especially important element for growth, feed efficiency and proper metabolism of aquatic species. Plant based feeds for aquaculture already include large amounts of phosphorus; however, much of this phosphorus is unavailable to fish because it is bound as phytate (40-80%). Fish, like many other species of animals are not able to degrade phytate, which is why they need a bit of help. Phytase is an enzyme that significantly raises the availability of phosphorus by catalyzing its release from phytate. It significantly lowers the need for large amounts of inorganic phosphorus and prevents accumulation of its bound forms in the pond water.
- Protein optimization – Proteins are essential for growth and development of every living organism, and aquatic species are no exception. Considering that their products are quite expensive, different strategies have been developed to reduce these expenses, one of the most effective being the use of proteases. Proteases are enzymes that break down long protein chains into smaller proteins, peptides and amino acids, which are readily digestible by aquatic species compared to the initial compound. Adding proteases to aquaculture feeds increases the efficiency of nutrient absorption, which means that smaller amounts of those expensive protein products are needed to fulfill the daily nutritive requirements of fish and other aquatic species. This practice can significantly reduce the expenses and amount of accumulated waste in the pond water.
- Carbohydrate optimization – Carbohydrates are the primary source of energy for many aquatic species, which is why their availability is critical for optimizing energy efficiency. Carbohydrates found in aquaculture plant feed can be split into two groups – non-structural and structural carbohydrates. The first group includes starch and simple sugars like glucose and fructose, which are readily degraded and absorbed by fish and other aquatic species. On the other hand, structural carbohydrates are plant fibers, usually found in plants’ cell wall, and they are extremely hard to digest without some help. Most aquatic animals naturally have a limited number of carbohydrases (enzymes which dissolve carbohydrates) in their arsenal and also differ greatly amongst themselves in their ability to digest carbohydrates. For this reason, incorporating exogenic carbohydrases can largely benefit them and help with feed conversion. Carbohydrases used in aquaculture include amylase, chitinase, cellulase, and xylanase.
- Lipid optimization – Another key component of aquatic species’ nutrition are lipids. They are especially important during early stages of development; their proper absorption can increase survival rates of larvae and reduce difficulties with metamorphosis. By adding lipase enzyme to the aquaculture feed one can significantly increase absorption of lipids in all stages of an animals’ development.