Pravin Mishra, DVM

Diverse gut microbiota plays a significant role in host metabolism, growth performance, nutrient digestion, and overall health of birds. The composition of chicken gut microbiota depends on age, especially at the early stages of life, genotype, farming conditions/environment, and diet/feed additives. Sometimes, the gut microbiota composition can be altered severely by non-infectious or infectious stressors. Consequently, this dysbiosis can impact intestinal morphology and activities (e.g., increased permeability of the intestine, higher risk of bacterial infection, sepsis, inflammation, and reduced digestion). Probiotics can affect the health, performance, and disease risk of the hosts, as they can amend the dysbiosis and improve the balance of gut microbiota in healthy hosts by reducing the proliferation of pathogenic species and increasing the beneficial bacteria. The most commonly used probiotic species belong to the genera Lactobacillus ,  Streptococcus ,  Bacillus , Bif

Probiotics are live microorganisms which, when administered in adequate amounts, confer health benefits to the host. The use of probiotics in poultry has increased steadily over the years due to higher demand for antibiotic-free poultry. The objective of this systematic review is to present and evaluate the effects of probiotics on the nutrient utilization, growth and laying performance, gut histomorphology, immunity, and gut microbiota of poultry. An electronic search was conducted using relevant keywords to include papers pertinent to the topic. Seventeen commonly used probiotic species were critically assessed for their roles in the performance and gut health of poultry under existing commercial production conditions. The results showed that probiotic supplementation could have the following effects: (1) modification of the intestinal microbiota, (2) stimulation of the immune system, (3) reduction in inflammatory reactions, (4) prevention of pathogen colonization, (5) enhancement of