Threonine, arginine and glutamine: Influence on broiler intestinal physiology

As such, a well-established gut microbiota brings benefits to the host, while microbial imbalance can contribute to the onset of disease and increase the competition for nutrients with the host.

In addition to causing direct morphological damage, diseases such as coccidiosis and necrotic enteritis (NE) can reduce the number of desirable groups of bacteria which modulate the host’s immune system (Antonissen et al., 2016).

Nutrition affects the composition of microbiota (Pan and Yu, 2014) and the functions that such microorganisms perform for the host.

Nutritional strategies aimed at the regeneration of injured intestinal mucosa have the potential to improve recovery through beneficial effects on the microbiota, digestive physiology, immune system and inflammation. Increasing the density of amino acids seems to be a possible way through which such beneficial effects can be generated.

• In particular, threonine (Thr), arginine (Arg), and glutamine (Gln) have been studied for their role in mucin production, immune function, and epithelial proliferation, respectively.

Coccidiosis and Necrotic Enteritis 

Coccidiosis is the most important parasitic disease in commercial poultry production systems and is considered a major predisposing factor for the development of NE. Considering that mucus provides a suitable substrate for the proliferation of Clostridium perfringens.

Two main components are responsible for maintaining the integrity of the intestinal mucosa:

>> The first one is the mucous layer, which acts as a barrier between luminal contents and the enterocytes that line the intestine.

>> The second component of the intestinal barrier is the enterocyte layer: the intestinal epithelium is constantly renewed as proliferating cells in the mucosal crypts differentiate and migrate to the top of the villi, where they are eventually lost by peeling. This renewal rate increases considerably during an intestinal challenge.

Intestinal inflammation in broilers infected with coccidia results in necrosis of the villi, which is characterized by a reduction in villi proportion: crypt, dilation of the crypts and depletion of goblet cells. As well as presenting increased expression of inflammatory genes (iNOS, IL-1β, IL-8 and MyD88).

Amino Acids and Intestinal Health

Besides its barrier role, the main function of the gastrointestinal (GI) tract is the efficient digestion and absorption of nutrients. In order to support these functions, nutritionists must understand the gut’s immune system and its relationship with the microbiota as an organ with specific nutritional needs.

Enteric challenges can alter the immune response and certain nutrients, such as amino acids, can become limiting factors when it comes to producing key proteins for an adequate immune function.