Diet is considered the most important input in poultry farming since it represents approximately 70% of the costs related to poultry production. The feed supplied to the poultry must be of high quality to fulfill the nutritional needs required by broilers, breeding birds, or laying hens. Each group of poultry has different nutritional requirements related to growth, development, and production.

On the other hand, the quality of the diet is closely correlated with the development of digestive problems if it does not meet the required conditions. This diet must contain the nutrients that the poultry need for the correct performance of all their organs and systemic functions. In the performance of the digestive tract of production poultry, there is a correlation between this system with others such as the immune system, endocrine system, or nervous system. Therefore, it must be guaranteed that the quality of the diet is optimal so that all systems work efficiently, and the poultry has intestinal welfare.

The digestive tract of poultry: its basic function

The digestive tract of production poultry is responsible for the uptake of nutrients that maintain a healthy and welfare state in poultry production. The feeding process starts at the beak when the poultry takes the feed to swallow it. It is recommended that the pellets are in good hygienic and manufacturing condition since their solid nature prevents problems of rapid transit when it is dusty. In addition, the poultry has a small number of salivary glands so they must swallow the feed immediately.

After going down the esophagus, the feed passes through the proventriculus where it begins its fermentation thanks to bacteria of the genus Bacillus and an acid medium. It then passes into the gizzard where the food is crushed by small stones, technically called gastroliths, which remain in the gizzard and allow it to be transformed into smaller particles. In addition, the medium becomes more acidic to digest some components of the food, which is now called cud.

Further on, the food bolus passes through the small intestine where it continues to be transformed by bile and pancreatic juices and a more alkaline medium. At this point, the food content is called chyle and at the end chyme. The small intestine is composed of the duodenum, jejunum, and ileum where most of the nutrients are absorbed. This portion of the digestive tract is characterized by villi which in turn have microvilli. In these tissues, there is a lining by enterocytes which are the digestive cells that absorb the nutrients provided by the quality diet.

Subsequently, the chyme passes to the large intestine formed by the two cecum sacs that characterize the poultry and the colon. In these portions of the digestive tract, there is a fermentation process by bacteria of the poultry’s microbiota that transform the food remains that were neither ground nor absorbed. Finally, the feces are formed in the colon and pass into the rectum to exit through the cloaca together with the uric acid produced in the urinary system.

Gut microbiota: a key principle of intestinal welfare

At hatching, poultry begins to pick up bacteria from the environment that will constitute their microbiota throughout life. This microbiota is a set of microorganisms including bacteria, viruses, fungi, and protozoa that live permanently in the poultry’s digestive tract.

Current research has focused on discovering the role of the poultry intestinal microbiota concerning digestive physiology, immune system, production efficiency, and general health.

The population of microorganisms, especially bacteria, is changing throughout the digestive tract. This process is regulated during rearing and defines the populations for the adult stage of the poultry. In the anterior organs such as the proventriculus, there is a predominance of Lactobacillus as they survive in acidic environments. In the small intestine, the bacterial population continues to be dominated by Lactobacillus, but other species such as Clostridium, E. coli, Salmonella, Streptococcus, and Enterococcus can proliferate. Subsequently, the small intestine, due to the low oxygen environment caused by fermentation processes, is characterized by significant populations of Clostridium.

Some of the bacteria presents are associated with digestive disease processes when their populations increase abruptly. The microbiota can be affected by changes in feed, environment or management, or the quality of the diet. Once this balance is disturbed, the environment of each portion of the digestive tract can change and lead to alterations in the populations of microorganisms. This microbiota remains on the epithelium of the digestive system creating a natural barrier when it is in optimal conditions. Once this barrier is altered, the predisposition to the entry of external pathogenic microorganisms or the growth of harmful bacteria increases.

The quality of the diet in digestive problems

The feed manufactured for poultry production is a feed composed of a mixture of raw materials from cereals and sub-products. In addition, it also includes vegetable proteins, vitamins, minerals, amino acids, and additives. This composition aims to fulfill the nutritional needs of each type of poultry for correct growth and productive efficiency.

Poultry nutritional needs

Each production system requires a different nutritional composition. In the case of broilers, the feed is characterized by having a large amount of metabolizable energy, since these poultry have a high metabolic rate for their growth. Likewise, they require an important amount of protein in the diet for muscle formation in a few days. In addition, there is a high demand for copper, iron, and zinc, which are necessary for various cellular and physiological processes in broilers (Table 1).

On the other hand, laying hens have nutritional needs related to egg production. Therefore, the high demand for calcium stands out, since it is the element that conforms to the eggshell and the bird’s bones with 96% calcium carbonate.

Thus, the quality of the feed in terms of its composition is essential to avoid diseases due to deficiencies in each type of production.

Digestibility of poultry diets

The raw materials used for the manufacture of poultry feed are mainly based on corn or soybean. These products are characterized by high values of metabolizable energy and vegetable protein. However, they also have anti-nutritional factors that must be counteracted during processing. Therefore, the quality of the diet is significantly correlated with the optimization of the industrial processes carried out on the raw materials.

There are several anti-nutritional factors in soybeans, including lectins, lipases, saponins, lipoxidases, anti-thyroid factors, among others. These molecules interfere with feed absorption and affect the cellular processes of the digestive system in poultry.

On the other hand, the digestibility per se of the diet can cause difficulties to the poultry for its digestion and utilization (absorption). Digestive enzymes can be insufficient to process food and thus generate lower productive performance. This is especially true for the digestion of the vegetable fiber that makes up soybean and corn.

Quality of raw materials in poultry farming

Raw materials are the components used to manufacture the feed consumed by poultry production. In poultry farming, they are derived from grains such as corn because of their high nutritional value. However, these raw materials are subject to international market conditions as they are considered commodities. For this reason, their prices vary worldwide depending on conditions such as transportation, climate, availability, and demand.

The feed used to feed production poultry can vary in quality due to changes in its raw material composition to respond to economic difficulties.

During 2020 and 2021 the price of these raw materials increased significantly so producers have changed the quality of the diet supplied to decrease costs. These changes in the poultry feed, with lower quality and abrupt alterations in its origin, affect the intestinal welfare and predispose to digestive pathologies such as necrotic enteritis.

Intestinal welfare of production poultry

The intestinal welfare of poultry is correlated with an optimal state of the epithelial barrier that composes the digestive system, as well as with a balanced microbiota. Infectious processes by bacteria, viruses, or protozoa (coccidiosis) can cause lesions in the barriers of the digestive system, which affects the absorption of nutrients. Therefore, the consumed food remains less time in the tract and is eliminated without being completely absorbed.

The alteration of the intestinal welfare has consequences that affect the health of the poultry. Thus, imbalances of the digestive system appear, the nutrients available in the large intestine increase, where the bacteria present multiply uncontrollably and can colonize the small intestine. This process generates dysbiosis and increases the poultry’s transit, which prevents them from absorbing nutrients from the diet.

Presence of mycotoxins

Mycotoxins are metabolites of fungal origin that contaminate poultry feed during cultivation or storage. These molecules have a pathogenic effect on the digestive system of poultry when consumed.

The mycotoxins DON, T2, Fumonisin, or Ergotamine have serious effects on the organs of the digestive system, causing problems such as diarrhea, malabsorption syndromes, decreased feed intake, and even gizzard hemorrhages. These toxic molecules are a severe problem in poultry farming since poultry are the most affected species when they consume them. The quality of the diet must be optimal, and the presence of mycotoxins must be reduced during feed processing.

Strategies for improving intestinal welfare in poultry

High-quality diets need in turn a digestive system in optimal conditions to take full advantage of this feed. Therefore, it is recommended to improve the intestinal welfare that guarantees the correct functioning of the digestive tract of the poultry according to their needs. Several strategies allow improving this intestinal welfare in the poultry and obtaining better productive performance.

• Use of exogenous enzymes: The use of Alquerzim optimizes the digestive processes in the poultry as it provides exogenous enzymes to improve digestion. This strategy is aimed at improving the absorption of nutrients from feed containing corn, wheat, rice, and soybeans. In this way, the poultry (especially young chickens) can obtain enzymes that allow them to digest and process the consumed feed and take advantage of the maximum amount of nutrients.
• Use of mycotoxin binders: Alquerfeed Antitox is a mycotoxin binder composed of the Silicoglycidol molecule. This product has a broad spectrum of action, blocking the effect of the number of mycotoxins that can affect the poultry. In addition, it is effective at any pH within the digestive tract and does not interfere with the absorption of the nutritional components of the diet.
• Minimize the impact of environmental or management changes since these processes generate acute stress processes. This stress can decrease the functionality of the immune system and predispose to infectious diseases or alterations of the poultry’s microbiota.
• Add Alquermold Natural to the poultry diet to obtain the antimicrobial effect of cimenol ring and citric acid. Cimenol ring is of natural origin and has bactericidal and fungicidal activity through the perforation of the cell membrane of these microorganisms; it also inhibits the synthesis of the ergosterol they need. Citric acid provides a synergistic effect since it interferes with the cell metabolism of pathogens and facilitates the entry of the cimenol ring. Alquermold Natural is a natural preservative that also controls the proliferation of intestinal pathogens such as Salmonella, Clostridium, and coli.
• This product has demonstrated efficacy in broiler field trials conducted in the United States, Colombia, and Peru. In these trials, it was shown that Alquermold Natural controlled necrotic enteritis, improved productive performance, and decreased the need for antibiotic growth promoters.
• Provide fresh drinking water sources since hydration plays a key role in digestive physiology processes.

CONCLUSIONS

Diet quality is a factor of significant importance in poultry farming since feed is the costliest input in production. In addition, nutrition determines to a great extent the success of a poultry production system.

The digestion of the poultry has particularities that must be considered since their welfare and function are relevant for the digestive problems that can be generated. The microbiota has a key role since it has functions of protective barrier and maintenance of a balanced environment at the digestive level.

Diet quality is correlated with several issues that must be considered. On the one hand, broilers have different nutritional requirements than layers, so the feed must be formulated in detail according to their needs. In addition, the raw materials used may contain anti-nutritional factors that must be counteracted during industrial processing of the diet if it is of high quality. Added to this, intestinal welfare is correlated to the integrity of the epithelial and their correct digestion and absorption function in each portion. Otherwise, digestive problems become relevant and affect the health of the poultry and worsen their productive performance. Finally, the presence of mycotoxins plays a key role since they are present in the feed and have serious effects on the poultry.

Finally, there are strategies to improve the quality of the diet and take care of the intestinal welfare of the poultry. This allows maximum utilization of nutrients, reduces costs related to treatments, and enhances the productive performance of the poultry. These strategies are correlated with the addition of exogenous enzymes, mycotoxin binders, and products that improve the intestinal welfare of the poultry.