Abstract
BackgroundThere are many diseases in poultry, many of which are caused by poor immune function. It is not clear how cytokines and various immune cell functions change with age in modern broilers. The purpose of this study was to explore the patterns of development of the immunity of the broiler chickens in cage.ResultsThe results showed that there were 3 development patterns of immunity in the broiler chickens. The first pattern was Down-Up. Cytokines and some immune indicators first decreased and then increased, and the lowest levels of immunity basically occurred from d 6 to 13. The second pattern was Up-Down, and from d 30 to 34, the highest levels of non-specific cellular immunity components, such as the peripheral blood mononuclear macrophage ratio, specific cellular immunity components, such as the peripheral blood helper T (Th) cell ratio and T cell and B cell proliferation activity, and mucosal immunity components, such as the ileal CD4, TGF-β1 and IgA mRNA levels, were observed. The third pattern was Up-Up, and the levels of the non-specific cellular immunity components, such as the serum nitric oxide (NO), C3 and C4 levels, the specific cellular immunity components, such as the spleen index, peripheral blood IL-2, IFN-γ/IL-4, cytotoxic T (Tc) cell ratio, and splenic NF-κB mRNA levels, the humoral immunity components, such as the serum IgG level, the mucosal immunity components, such as the ileal MHC-II, CD3d, TCRβ subunit, TCRζ subunit, IFN-γ, pIgR mRNA and ileal mucosa sIgA levels, were continuing to increase from d 1 to 34.ConclusionsIt could be concluded that the immune system and its function have not developed well in the broiler chickens d 6 to 13 and that the immune system does not mature until d 30 to 34 in the broiler chickens in cages. It is necessary to enhance the immune function of the broiler chickens through nutritional measures from d 1 to 30.
Highlights
There are many diseases in poultry, many of which are caused by poor immune function
Immune function first decreased to a certain age; the lowest point of immune function basically occurred from d 6 to 13 and immune function continued to increase until d 34
This study shown that the T cell immune development in the peripheral immune organs of broiler chickens was stronger at approximately d 35, and these results were similar to those found in our study at d 24 and 36
Summary
There are many diseases in poultry, many of which are caused by poor immune function. The growth and development of immune organs directly determine the overall immune function of birds and affect their resistance to various antigens and stresses in their living environments [3]. Epidemiological and experimental studies provide increasing evidence that the “growth” of the immune system occurs early in life and depends on the role of the intestinal microbiota [10]. This type of intestinal bacterial ecosystem is disrupted by antibiotics early in the lives of animals and may potentially affect the function of the immune system later in life [10]. Understanding the development of the immune system during chicken growth is a prerequisite for identifying new immunomodulatory factors and strategies
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