Applications of In Ovo Technique for the Optimal Development of the Gastrointestinal Tract and the Potential Influence on the Establishment of Its Microbiome in Poultry

Abstract

As the current poultry production system stands, there is a period of time when newly hatched chicks are prevented from access to feed for approximately 48–72 h. Research has indicated that this delay in feeding may result in decreased growth performance when compared to chicks that are fed immediately post-hatch. To remedy this issue, in ovo methodology may be applied in order to supply the embryo with additional nutrients prior to hatching and those nutrients will continue to be utilized by the chick post-hatch during the fasting period. Furthermore, in ovo injection of various biologics have been researched based on the ability of not only supplying the chick embryo with additional nutrients that would promote improved growth but also compounds that may benefit the future health of the chicken host. Such compounds include various immunostimulants, live beneficial bacteria, prebiotics, and synbiotics. However, it is important to determine the site and age of the in ovo injection for the most productive effects. The primary focus of the current review is to address these two issues [the most effective site(s) and age(s) of in ovo injection] as well as provide the framework for the development of the gastrointestinal tract (GIT) of the chick embryo. Additionally, recent research suggests the colonization of the microbiota in the developing chick may occur during the late stages of embryogenesis. Therefore, we will also discuss the potentials of the in ovo injection method in establishing a healthy and diverse community of microorganisms to colonize the developing GIT that will provide both protection from pathogen invasion and improvement in growth performance to developing chicks.

Expert consensus document: The International Scientific Association for Probiotics and Prebiotics (ISAPP) consensus statement on the definition and scope of prebiotics

“…Dietary pre biotics, including inulin, yeast cell wall extracts, lactulose and GOS are usually fed at concentrations up to 0.2% (weight/volume) of diet [140][141][142][143][144][145][146] .…”

In ovodelivery of various biological supplements, vaccines and drugs in poultry: current knowledge

“…Early chick feeding is essential, and research reports reveal that delayed feeding access led to decreased growth rate, reduced feed conversion efficiency, extended the time of marketing body weight (BW), and increased the mortality . On the other hand, early intake of external feed after hatching is associated with rapid development of organs and GI tract . The GI tract is the most rapidly developing organ in the later stage of incubation, making up to 1% of the weight of the 18‐day‐old embryo and reaching 3.5% at hatch …”

<b>Effect of oral dietary supplement for chicks subjected to thermal oscillation on performance and intestinal morphometry

“…Controversially, Roto et al (2016) emphasize that in situations of high temperatures, the opposite is observed, that is, there is a reduction in the weight of the intestine, as a consequence of a physiological adjustment in an attempt to reduce the production of corporal heat.…”

“…The period immediately after hatching is crucial for the development of chicks due mainly to the morphophysiological events of the gastrointestinal tract (Boleli, Maiorka, & Macari, 2008;Roto, Kwon, & Ricke, 2016).…”

“…Ingestion of exogenous foods is accompanied by a rapid development of the gastrointestinal tract and associated organs to ensure the maximum assimilation rate of the ingested nutrients (Karasov & Douglas, 2013;Roto et al, 2016).…”