ReviewNanoparticles in feed: Progress and prospects in poultry research

•Nanoparticles offer fast and direct delivery of new or tailored properties for improved poultry health.•Poultry nutrition using nanomaterials produces changes to the understanding of chicken health in the poultry industry.•Delivering essential nutrients using nanoparticles has been shown to demonstrate promise in poultry research.

The global poultry industry has greatly expanded due to an increase in demand for chicken meat and eggs. Growth of the industry was followed by growth in research which resulted in improved growth rate, feed efficiency, health status, and reduced carriage of pathogens. However, major research focus was improvement in productivity. It is possible to manipulate feed formulations to improve the feed conversion ratio (FCR), which results in a lower feed requirement to achieve market weight. Feed additives, containing vitamins and minerals, are commonly added to typical diets to support rapid growth and favourable FCR. Nanoparticles can be added to feed and provide an excellent platform to incorporate in various compounds, such as vaccines and nutrient supplements, due to large surface area to volume ratio and high absorption in the body. Nanoparticles can enable direct transportation of compounds to targeted organs or systems while avoiding fast degradability often seen with antibiotics and can encourage multiple health benefits. Silver, currently the most common nanoparticle investigated for use in chicken feed, has been shown to improve the microbiota of chickens. However, the positive results are tempered by the finding that silver nanoparticles have relatively high toxicity in birds. The question therefore arises as to whether other nanoparticle forms of essential metals and natural compounds can be safely delivered to provide positive impacts on health and productivity without the toxic side effects that can be seen with silver nanoparticles. Here, we review the current state of nanoparticle use as a poultry feed supplement - the successes and pitfalls of nano-feed as reported by researchers across the world.