Broiler chickens from: "Determination of the immunomodulatory properties of levan as a poultry feed additive"

<p>The poultry immune system is a complex, plastic and multifactorial unit whose functions are influenced by the age of
the birds, feed composition, feed and energy intake, genetic growth potential, environmental factors and stress. The
digestive system is a very important organ system from the point of view of immunity. This is due to the fact that the
main function of the intestines is to digest food and absorb nutrients from their lumen into the bloodstream, which
keeps the intestinal epithelium in constant contact with large amounts and a wide variety of antigens derived from
exogenous sources. The microbiome of the poultry digestive system is also important in maintaining an appropriate
level of immunity. The plasticity of the bird&#39;s immune system and its high sensitivity to external influences have led to
many attempts to manipulate immune functions, including vaccination, reduction or elimination of specific pathogens,
the use of antibiotic growth promoters, and nutritional immunomodulation. One of the substances that can exert an
immunomodulatory effect and that can be used in the nutritional immunomodulation of poultry is levan. Due to the fact
that levan is produced by probiotic bacteria used in animal nutrition, the influence of long-chain fructans of the levan
type on the performance and health of various animal species such as pigs, broilers, rats and fish was investigated. It has
been shown that it stimulated the immune response of fishes and improved the performace of farm animals. The aim of
these study is to determine the immunomodulatory properties of levan as a feed additive for poultry. Basic research on
poultry will allow to determine whether levan has immunomodulatory properties in the gastrointestinal tract of birds
and, above all, what these properties are and what are the mechanisms of their action. However, it should be
remembered that the application of nutritional immunomodulation may have some unintended consequences that will
result from the interaction of immunomodulatory nutrients with other nutrients and their effects on physiological
aspects other than just immune function changes. This issue is often overlooked by researchers, therefore it is
important that any results are interpreted in the context of the whole bird, with an emphasis on its productivity. The
experiment will consist of two stages. The first stage will cover laying hens and the second stage will cover broiler
chickens. In the case of hens, 120 birds will be used in the experiment, which will be divided into 5 experimental groups.
Each group will consist of 8 replications and each replication of 3 birds. In the case of chickens, 1400 birds will be used in
the experiment, which will also be divided into 5 experimental groups. Each group will consist of 8 replications and each
replication of 35 birds. Both in the case of hens and chickens, the layout of the experimental will be identical - the first
group will receive a standard feed mixture without any additive, the second group will receive a standard feed mixture
with 0.1% levan, the third group will receive a standard feed mixture with 0.25% levan, the third group will receive a
standard feed mixture with the addition of 0.5% levan, and the fourth group a standard feed mixture with the addition
of 1% levan. Morphological and biochemical blood tests will be performed in both laying hens and broiler chickens to
identify possible immunomodulatory properties of levan. The following will be determined in the blood: the total
number of leukocytes, the number of individual groups of leukocytes, the ratio of heterophiles to lymphocytes, levels of
ALT, AST, ALP, LDH, gamma globulin, albumin and acute phase proteins. In birds, the composition of the gastrointestinal
microbiome, the composition of intestinal mucin will also be determined, and histological and immunohistochemical
tests will be performed on selected sections of the small intestine, caecal tonsil, thymus, spleen and bursa of Fabricius.
The role of immunomodulation in relation to the bird as a whole will also be determined. For this purpose, the
production parameters of the birds will be monitored and then correlated with the individual immune functions.</p>