Over a decade ago, when enzymes were first added to animal diets, the supplementation was limited to using phytase to reduce phosphorus excretion. Although enzyme supplementation in animal feed has been used for many years, it was initially superficial, mainly focusing on enzyme technology research in animal feed.
A deeper understanding of enzyme use in diets emerged as the demand for high-quality protein continued to rise across North America and globally. With advancements in management and livestock technology, animals are now raised for relatively short periods. Therefore, farmers need to maximize that time efficiently to meet the increased protein demand, including making the most of the feed.
Producers need to be more adept at optimizing livestock production in a sustainable way—and enzymes offer an opportunity to do just that.
Incorporating Indigestible Ingredients
Poultry and swine diets typically include easily digestible staple ingredients like corn and soybean meal. A corn-soybean meal diet has a digestibility rate of around 85%, with the remaining 15% undigested. In young animals, the proportion of indigestible feed increases due to their bodies not producing enough endogenous enzymes for breakdown.
These expensive ingredients are not only underutilized but can also have adverse effects on the gut. Undigested nutrients cause intestinal irritation and diarrhea, affecting nutrient absorption. This is an issue that enzymes can help address.
Additionally, North American nutritionists are finding more potential alternative ingredients during periods of raw material price fluctuations. This also creates a challenge because these ingredients have low digestibility rates and contain various anti-nutritional factors.
Three types of enzymes—phytases, carbohydrases, and proteases—will be discussed in this article regarding their specific roles and effects on animals and benefits for producers.
Basic Functions and Benefits of Enzymes
Although all enzymes function similarly when added to feed—improving animals’ ability to digest coarse ingredients—nutritionists can use them through various approaches. Each enzyme has different characteristics that affect the supplementation rate: the need for a protective coating, the site of action in the animal’s gut, and their overall effectiveness.
One interesting and important aspect of enzymes is that each type has a specific role in the animal’s body. Each enzyme works on a specific substrate to initiate chemical reactions within the body. However, a particular enzyme is only suitable for a specific substrate—similar to a lock-and-key mechanism.
The benefits of enzyme supplementation can be seen in the following aspects:
- Reducing Feed Costs through Matrix Utilization
- Growth or Feed Efficiency can be improved by releasing nutrients, leading to reduced cost per kilogram of meat
- Enzymes may also play a role in managing gut health. High-fiber diets can increase gut viscosity and fermentation processes, which may lead to mortality in animals. Pathogenic bacteria can also thrive in excess nitrogen diets.
While phytases and carbohydrases have been used for a long time, proteases have recently been added to the list of feed additives. It is important to note that each enzyme breaks down a specific substrate. Not all enzymes are alike in structure and mechanism.
Mechanisms of Enzyme Action
Here is an overview of how nutritionists can use these three types of enzymes to benefit livestock and producers.
- Phytase
The substrate of phytase is phytic acid, a form in which phosphorus is stored in plant tissues. Phytic acid is detrimental to livestock because it binds to minerals and amino acids, making them unavailable to the animals. This leads to the excretion of beneficial nutrients, reducing productivity.
Phytase has been added to animal diets for over a decade. As mentioned, the primary goal and mechanism of phytase is to reduce phosphorus excretion, which saves costs in the diet. Initially, this savings was related to reducing phosphorus costs in the diet, but nutritionists can also flexibly reduce soybean meal amounts by improving amino acid digestibility.
- Carbohydrase
Carbohydrase enzymes include xylanases, glucanases, and amylases. They act in the stomach to break down carbohydrates such as fiber, starch, and NSP into simple sugars to provide energy for the animal’s use.
Cereal sources like corn, barley, and wheat have an outer bran layer. Most of this layer is physically broken down during feed production but not entirely. Animals cannot digest the fiber of the cell walls, and this proportion is 10-20%. Carbohydrases break down and decompose these starch-rich molecules.
One of the most common carbohydrases is xylanase. Xylanase breaks down the arabinoxylan structure in corn or wheat, allowing animals to absorb these components as an energy source. This limits the need for fat or energy supplementation in fattening diets.
- Protease
Protease is the newest technology compared to other enzymes, with animal and plant proteins as its substrates. It breaks down anti-nutritional factors related to various proteins. Protease improves protein digestion and increases amino acid availability, releasing valuable nutrients. As a result, it enhances animal growth and productivity, minimizing adverse effects from undigested protein in the hindgut.
Ingredients with low amino acid digestibility are most affected by exogenous proteases, which is why protease use is most effective when alternative ingredients are used in the diet. Protease helps producers manage nutritional risks associated with feed quality and allows them to make the best use of all available feed ingredients.
Protease is not limited to diets with alternative ingredients. Animals fed a basic corn-soybean diet cannot fully utilize 100% of the protein. Therefore, adding protease to a corn-soybean diet will enhance amino acid digestibility and animal productivity.
Future Use
The benefits of enzyme use are becoming increasingly clear as more research is conducted. For animals, enzymes help optimize gut health, promote even growth, and enhance overall health. For producers, they reduce feed costs and improve profitability.
Each type of enzyme has a distinct function and, therefore, does not interfere with one another. The key is that enzyme use will continue to evolve as we learn more about each production technology.