**1.1 Global significance of poultry production**

Remarks of [3] indicate predicted human population by 2050 is 2097 millions means expecting addition of 877 million to the existing population of 1220 millions.

As of now the available eggs are 58no's, and meat is of 2.2 kg/capita/annum [4]. As per [4] report growth rate of poultry industry is 7.52% and 8.51% in broiler and layer respectively to cater the needs of animal protein demand. Conversely, the projected growth and production output was mainly depends on availability of quality feed ingredients, over and above the emerging and reemergin diseases.

The growth and development of poultry industry is crucial in sustaining the supply of safe, nutritious and good quality protein sources to balance the diet composition of humans. Productive performance of poultry had influenced by the host factors like: genetic background (bird species, type of bird, breed and sex), gut development and maturation (immune system, gut morphology and micro biota acquisition) and stress (environmental factors, type/form of feed, poor management, health interventions, litter management, nutrition). Gut health is a major concern and more complex with more than 640 different species of microbiota, over 20 hormones which digest and absorb the majority of the nutrients accounts 20% of energy utilisation [5]. It infers that factors fatal to gut certainly influences the nutrient intake as well as compromised output.

A healthy gastro intestinal tract (GIT) will be able to efficiently carry out activities viz. protection against insults (infectious and non-infectious), transport of ingested feed and digesta through the entire track, digestion, absorption process, hosting microbiota and excretion of undigested feed. Whereas, it may not be possible with a compromised GIT due to various deviations. Factors like nutrients/feed; microbiota and environment/stress will influence the functionality, integrity and health of gut.

#### **1.2 Factors to be considered for good gut health**


Here in this chapter is an insight into the role of gut health and integrity, through their roles, in modulating bird's ability to be resilient towards the infections on immunity and production.
