This is part 2 of a 4-part series exploring how epithelial integrity is the first line of defense to target immunomodulation, BCO and food safety issues. Catch up on Part 1 here.
The immune system is a complex network, comprised of physical barriers and specialized cells. It provides both passive and active defense against harmful substances and pathogens. Inflammation is crucial for the bird´s defense, but the process consumes high levels of nutrients. As a result, prolonged, or chronic, inflammation can impair performance. That is why immunomodulation is key to poultry welfare and performance.
Immunomodulation refers to an animal’s ability to regulate the immune response. When a bird becomes infected, an inflammatory response must be triggered aimed at eliminating the pathogen and, ultimately, healing or repairing. Equally important, however, is the ability of the immune system to shut inflammation down once the challenge has been neutralized. This will allow the bird to resume utilizing those nutrients for performance, rather than fueling the inflammatory response.
There are two arms of the immune system, referred to as the innate and adaptive immune responses. The innate immune system is non-specific – without memory – and triggers a cascade of immune events that start with unspecific white blood cells that attack any antigen that infects the bird. The adaptive immune system is more complex. The adaptive immune system develops cells and immunoglobulins that will target and remember specific antigens. The adaptive immune response is much more efficient in terms of nutritional requirement and causes less tissue damage.
The goal of the immune system is to kill pathogens and restore homeostasis, but it’s even better to avoid the infection in the first place. This is where epithelial integrity comes into play. The epithelium is one of the most important parts of the innate immune system and serves as a physical barrier that keeps antigens out of birds’ organs. The two major sites of infection – the intestinal and respiratory tracts – have structures in place to assure epithelial integrity.
The cell lining, tied together by tight junctions, plays an important role in sustaining the epithelial integrity and avoiding uncontrolled immune stimulation. This helps prevent the organism from becoming infected. Evidence shows that stressors, such as heat stress can weaken tight junctions and lead to chronic inflammation.
Inflammation and especially innate immune activation are very costly in terms of nutrient utilization. When the immune response persists and chronic inflammation occurs, nutrients and energy are diverted away from animal performance, which includes growth, reproduction and feed efficiency as well as meat, milk or egg production.
When an animal is not receiving adequate levels of energy and nutrients, it will begin breaking down muscle to supply that demand. This might further reduce meat yield, depending on the severity and length of the challenge.
The combination of both local and systemic effects of excessive or chronic inflammation is alarming. Sometimes the symptoms are hard to read, and it may be silently jeopardizing animal performance and profitability of the operation.
Ensuring that trace mineral requirements are met is critical for the animal to cope with daily challenges in production. Whether or not an animal’s trace mineral requirements are being met depends on not only the amount supplemented but also the trace mineral source, the amount of antagonists in the diet/water and the stress level.
Zinc helps maintain epithelial integrity by strengthening the bonds between the cells that line the gastrointestinal and respiratory tracts. The epithelial integrity is also sustained by the antioxidant effects of zinc and other minerals such as selenium.
Manganese, along with zinc, participates in mucin production to help avoid infection in the first place. This improved integrity reduces immune activation and inflammation, saving nutrients for its primary function: muscle growth or egg production.
Chromium is also reported to have beneficial effects on immune competence of birds at cellular and humoral levels, by decreasing circulating corticosterone, especially in stressed animals, improving performance and welfare. Corticosterone, a hormone released during periods of stress, is an immune suppressant.
Supplementing poultry diets with zinc from Availa®Zn can help manage inflammation by strengthening the bonds between the epithelial cells in the gastrointestinal and respiratory tracts and maintaining tight junctions. A summary of 23 trials showed intestinal strength was enhanced by more than 15% in poultry supplemented with zinc and manganese, or a combination of both, from Zinpro Performance Minerals® versus poultry diets supplemented with inorganic forms of the same minerals.
Research has shown an increase in proliferation and activity of different immune cells, with higher tumoricidal activity of macrophages in broilers supplemented with Zinpro Performance Minerals compared to birds supplemented with inorganic sources alone. Feeding zinc from Availa-Zn has been shown to elevate the sensitivity to lipopolysaccharides (LPS) from Salmonella typhimurium injected in layer hens, resulting in a faster decline in fever and circulatory Interleukin-1 β, a potent pro-inflammatory cytokine. This means a more rapid and robust response, shortening the acute phase response and allowing a quicker return to homeostasis.
Higher Interleukin-10 (IL-10) levels were observed in the ceca of broilers fed Zinpro Performance Minerals, challenged with Eimeria spp. IL-10 is an important anti-inflammatory cytokine, responsible for balancing the immune response, avoiding an overshooting of inflammation.
Through multiple mechanisms, Zinpro Performance Minerals effectively modulate the immune system, improving performance and profitability. To learn more about including performance trace minerals in your poultry nutrition program, contact your Zinpro representative today.
*Note: Not all products available in all markets