Date: 26/04/2021

When formulating feed and foods for animals certain important factors must be considered in order to maintain the efficiency of the product and a good uptake within the market. In animal nutrition the choice of raw materials, for example, must be made based on analyses such as chemical composition, palatability and digestibility.

In order to evaluate the value for money of an ingredient and optimize production, we need to not only choose substances that are rich in nutrients, but also guarantee that they are fully processed by the animal’s system. This process may vary according to the ingredient and the species, and calculating it is done via tests which determine the digestibility coefficient in each case.

By choosing ingredients that display high digestibility, feed formulators can improve on the efficacy of their products, guaranteeing the correct preservation of nutrition and animal health along with the quality and authority of the brand within the market.

What is digestibility in animal nutrition?

Digestibility is the factor that expresses the potential of an ingredient to be digested, absorbed and processed by the animal’s system, whether in terms of nutrients or of energy.

It is very important that this coefficient is known when companies that make feed and animal foods are making decisions. This is because it helps in the choice of ideal raw materials, depending on the species and the type of food being produced.

With innovation and new developments, both in the market and in research, staying up to date on the digestibility of ingredients is the best way to optimize production and reduce costs. In the end, companies that formulate animal feed can evaluate the ingredients used and swap them out if they find new alternatives with better value for money.

Choosing nutrient rich substances without knowing their digestibility rate risks jeopardizing the tangible efficiency of the feed. Low digestibility in animal nutrition can cause animals to lose weight and display nutritional deficiencies, even if the nutrients are apparently present in the nutritional table of the food.

In this context it is possible for formulators of feed to invest in ingredients that are rich in nutrients, but that will not be assimilated, since they are not digested by the animals. Since this is the case, the only way to guarantee that nutrients added to the product will really be absorbed, is by knowing and prioritizing the quality and digestibility of each element.

Main factors that affect digestibility

Digestibility in animal nutrition can vary according to the type of food, basic materials used, or even the animal that will eat the feed. According to the International journal of Agriculture & Biology, some of the factors that most heavily affect the efficiency of digestion are:

Consumption of feed

The quantity of feed consumed can affect digestibility depending on whether large quantities are consumed, or smaller portions over the course of the day. When the animal eats often and in large quantities, digestion is affected due to retention of food in the digestive tract over shorter periods of time.

Particle size

The size of the flakes or grains of the feed can also influence digestibility in animal nutrition. The “Different grinding gauges in dog diets” study, by the UFSM, in 2009, shows that very fine particles can accelerate the passage of food in the digestive tract, causing the nutrients to be less fully assimilated due to lower absorption.

However it is also worth noting that the ideal particle size can depend on the species and age of the animals, making specific recommendations for each formulation and commercial goal necessary.

Chemical composition

The chemical composition of feed or animal foods is one the biggest factors in deciding digestibility. This is because, as noted in the International Journal of Agriculture & Biology, the chemical composition of any animal food can contain many different quantities of materials that may reduce the efficacy of digestive enzymes. 

On the other hand, an ideal chemical composition can improve digestibility by the addition of soluble proteins and/or carbohydrates, such as isolated proteins.

Processing of the food

The processing can influence not only the digestibility, but also the palatability of feed. Changes to the physical shape can make the food more or less attractive to animals, as well as changes to the texture, grain fineness and particle size.


Animal age directly influences their relationship to, and their capacity to digest, certain foods. Particularly old or young animals have particular needs in relation to food texture and nutritional composition, since the digestive system works differently at these stages.

To improve digestive efficiency in animal nutrition, specific ingredients should ideally be chosen for formulations intended for adults and young, with the perpetual aim of improving nutrient absorption and assuring high palatability.

The importance of connecting digestibility to palatability

Summed up, palatability refers to the attractiveness of a food for the animal in question. As such, factors such as taste, texture, appearance and smell need to be analyzed and improved upon.

There is no point in offering nutrient rich, easily digested feed to the animal if it refuses to eat it due to some characteristic of the food it does not like. This behavior will result in the animal weakening and displaying shortcomings, driving the owner or manager to look for other options.

For this reason, in order to grow stronger within the market, and to be a well-regarded feed formulating company, with market authority, it is essential to care for and guarantee quality in areas such as nutritional value, digestibility and palatability.

Ingredients that increase digestibility in animal nutrition

Poultry offal meal

Being rich in amino acids and in minerals such as phosphorus and calcium, poultry offal meal is an excellent option for formulating feed which is accessibly priced and has high palatability. Using this ingredient as a raw material in feed for pigs, fish and pets is very efficient.

There are ingredients on the market that stand out for their efficacy and fabrication processes.  An example of this is poultry offal meal, which is produced by cooking, pressing and grinding meat offcuts, poultry offal, giblets and cartilage. These ingredients are processed within hours of extraction, which guarantees a fresh, high quality raw material.

In relation to digestibility, Standard Poultry Offal Meal shows a minimum rate of 64% in tests with 0.02% pepsin.  Standard has indices between 56% and 60% when it comes to crude protein.

Another effective option in terms of Poultry Offal Meal is the Low Ash type. It is differentiated by a lower ash content and a higher crude protein content. In this case the rates vary between 64% and 73%.

Pig hide meal

Pig hide meal stands out due to benefits such as a high protein content, high palatability and high digestibility. . In quality meal, the isolated proteins ensure the material has at least 80% crude protein content.

The production process is via cooking, pressing and grinding unprocessed pig hides. As well as the natural high palatability of the product when offered to animals, this ingredient also offers a digestibility rate of at least 90% in tests with 0.02% pepsin. Pig hide meal can be used as a key ingredient in pet food.

Feather meal/ Blood and feather meal

Meals derived from feathers or feathers and blood are protein rich products that can be used as ingredients in the formulation of feed. Due to their low cost they can replace other ingredients that show the same efficiency but at a higher cost.

Although they have high keratin levels, which might suggest low digestibility, it is important to bear in mind that they pass through a process of cooking under pressure and are then pressed, which changes the structure of the keratin that is present. After processing, the proteins and amino acids in the product become more available for absorption by the animal’s system, especially in the rearing and feeding of fish.

Feather meals can be used in the nutrition of fish, pigs and pets. With high quality material and rigorous checking in the production chain, in order to monitor the nutritional safety of the ingredients, it is possible to count on fresh raw material.

Chicken protein hydrolysate

Proteins with a greater biological value have a greater number of essential amino acids. Chicken protein hydrolysate has undergone a process of enzymatic hydrolysis, creating shorter chains of amino acids, called bioactive peptides. Since 90% have a molecular mass under 2000 Da, they assist in faster digestion and absorption, improving the functioning of the gastrointestinal tract.

This process improves the absorption of nutrients by the animal’s system, and thus the performance of the feed. It can be used in the formulation of food for pets, pigs and fish. There are high quality chicken protein hydrolysates on the market, that stand out for their crude protein level of 75%, minimum digestibility of 90% and low levels of ash.

In addition these chicken protein hydrolysates present very high palatability. According to studies, the use of this ingredient in aquaculture can improve the conversion and survival rates of animals, while reducing water pollution.  Because they are more attractive, more palatable feeds result in a higher consumption rate by animals, which carries with it various functional benefits.


For a formulated food to be successful on the market it is vital that it offers results, especially when it has to do with the nutrition, development, health and growth of animals.

In this context, investing in ingredients that offer good digestibility and palatability is one way to guarantee feed quality and thus reach the desired objectives, whether in private or commercial animal rearing.

Keeping ourselves up to date with innovations in the market is fundamental, in order to carry out possible switches that could add value to the final product and reduce production costs.

By analyzing these factors and making the right investments, formulating companies can optimize production, raise quality and productivity and improve the profitability of their products as well as strengthening themselves within the market.

In relation to the animals, investing in digestibility in animal nutrition guarantees better productive development in fish and pigs, as well as protecting the health and welfare of pets.