**8. Conclusion**

*Advances in Poultry Nutrition Research*

Immunomodulators like Corticosterone, ascorbic acid and 1,3–1,6 β-glucans.

Low protein (13.46% CP and 0.65% lysine at 66% threonine) diets at peak

*Gene expression related to nutrition in chicken.*

dietary regimen [57].

production in layers

**Table 2.**

**7. Bio markers**

and impaired gut permeability.

gensus level by PCR-RV, and ST at serovar level.

permeability at tight junctions and celluar energy status [89].

Nutragenomics is an emerging science which would reveals the diseases induced by nutrient availability or alteration in diets [88]. For sustainable poultry production there is an emerging need to trace the relationship between economic traits and

fibronectin 1 etc.

WYFC fed with LN diets.

stress related genes.

MOS Expression of 77 protein synthesis gene,

High and low nutrients (HN and LN) The gene expressions of Rheb, TOR, S6K1

Lead Down regulation of all sugar, peptide and

**Gene expression Reference**

Kumar et al. [81]

Xiao et al. [82]

Wang et al. [83]

Ebrahimi et al. [84]

et al. [85]

Cytokine gene expression (ILreceptors 4 and 15) in spleen-1β, IL-2,toll-like.

including superoxide dismutase 1, lumican, β 2-microglobin, apolipoprotein A-1,

and 4E-BP1 in muscle were the highest in the

amino acid transporters. Up regulation of

Up regulation of MUC2 expression Kumari

Among the different diseases occurring in poultry, those caused by the genus Salmonella is the most common, causing serious economic losses to the poultry industry in terms of mortality, reduced growth and loss of egg production [89]. Some of the works [29] inferred that MHC-B haplotypes reactions were different towards genetic resistance against salmonellosis. Resistance to salmonella was linked to ILs, IFNγ, TLRs, iNO and apoptosis genes, and expression of IL-2, IL-6, IL-8 and IFNγ genes was higher, microsatellite analysis inferred [90] that MHC-1class was linked to colonisation to salmonella. Ocak et al. [91] noticed salmonella at

Determination of biomarkers to know the intestinal health is important breakthrough. Inflammation is the first sign of infection or injury to the system [92]. Baxter et al., [46] reported serum citrulline and IFN-È, cloacal IgA, are the potential biomarkers to identify the inflammation in intestine due to dysbacteriosis,

Alterations in gene expression of claudin-1 and occludin indicate mitochondrial respiration and ATP production variations which indicate the state of intestinal

Whereas oxidative stress is measured [93] by superoxide dismutase enzyme activity Thiobarbituric acid reactive substances produces during peroxidation and damage of the cells, break down of nitrite and nitrate produces nitricoxide which can be noted by griess assay to identify the concentration of nitric oxide in the cell [74].Pathogens like coccidian directly damages the epithlieal cells and loss of villous epithelia, results in decreased absorption [94]. Simple techniques like measuring the villi length, crypt depth and ratio are helpful standards to know the gut health. Villus height at duodenum, jejunum and ileum are 1400,900 and 700 mm and crypt

**108**

The gut represents a continuously evolving ecosystem where a dynamic interaction between host immune, neuroendocrine and entero-endocrine cells. The gut micro biota of the birds has influence on normal physiological development and homeostasis. Ban on AGPs make the evaluation of precision feeding as well as availability of various additives, phytobiotics, nutraceuitical…etc. are forcing the nutritionist to formulate the least cost rations for better production. Change in dietary regimen to boost immune system, minimise stress, good management and bio security practices are needed. Identification of genes/bio markers that regulates health and immune system is essential. Relationship among economic traits, dietary regimen and gene expression are the gaps. This review reveals that nutrition, immunity and stress are factors that influences the gut integrity in birds and production output.
