Yeast in layer diets: its effect on production, health, egg composition and economics

SUMMARYScientists throughout the world are increasingly interested in developing novel technologies and materials as alternatives to antibiotics in the poultry industry. The researchers' efforts include not just substituting antibiotic growth promoters in poultry feeds, but also reducing the total overuse of veterinary antibiotics in the poultry industry in order to achieve organic products. Several approaches have been applied as antibiotic substitutes, including the use of beneficial bacteria or medicinal herbs. Recently, using probiotic sources in a daily supplement regimen has become a common routine in commercial poultry production. For many decades, yeast and its derivatives were regarded as one of the most important microorganisms used in animal feed. Yeasts are important in several ecological processes for instance the dissipation of energy and carbon and mineralisation of organic material through the soil ecosystem as well as are involved in parasitic, mutualistic, symbiotic, and competitive interactions with other microorganisms. The combination of nutritional metabolites in the yeast-derived product induces the birds' health via balancing the immune system while heightening nutrient digestibility and gut health. Owing to prohibitions on using antimicrobial growth promoters, yeast-based products are becoming alternative supplements in poultry feed due to their health and nutritional advantages. Recently, several studies have shown that the inclusion of yeast in layer chicken feeds enhanced nutrient utilisation and increased egg production and egg weight. This review will discuss the uses of yeast in layer nutrition as an alternative method for organic poultry production to conventional growth stimulators.