In ovo feeding is a novel technique used to deliver various biologics and nutraceuticals directly
to poultry embryos prior to hatching. The purpose of in-ovo feeding is to improve the overall
health and performance of the hatched chicks. These injections are timed based on the embryonic
development stage and are usually performed on day 18 or 19 of the incubation period. Early
nutritional programming (in ovo injection) is one of the newest and most successful embryos
feeding methods to prepare chickens with healthy intestines, good microbiota, enhanced
immunity and improved overall growth performance. Nutraceuticals including amino acids,
vitamins and carbohydrates were typically employed for early feeding via the in ovo method,
along with feed additives like hormones, medications, exogenous enzymes, herbal plants and
their derivatives, immunostimulants, vaccines and other biological substances. The main focus
of current reviewis to provide an insight into applications and available findings related to in
ovo feeding on performance and health parameters of poultry, along with challenges and future
perspectives of this technique