Prenatal nutrition of poultry and its postnatal effects (review)

Fast growth rate in modern meat-type poultry is accompanied by several metabolic disorders resulting from the discrepancy between embryonic and postembryonic growth and development. Prenatal period of avian ontogenesis is characterized by abrupt physiologic and metabolic alterations and hence any disturbance at this stage can affect the hatch efficiency and subsequent postnatal growth and productivity (E.T. Moran, 2007; V.L. Christensen et al., 2004). The embryonic development in eggs can be supported by the in ovo nutrition using natural nutrients (amino acids, carbohydrates, vitamins) as well as growth stimulators and hormones; this approach can also prepare the poults for the intense postnatal growth (P.R. Ferket, 2016). From the nutrigenomic point of view, the nutrients and bioactive substances can affect gene expression (V.I. Fisinin et al., 2006; L. Bordoni et al., 2019). The experiments with the in ovo nutrition proved that the injections of nutrients can affect physiological status of broiler embryos and hatched broiler chicks. E.g. the injections of carbohydrates enlarge the pool of energy available for the embryo and decreases the catabolism of proteins and lipids during the final stage of incubation, resulting in the increases in the weight of the hatched chicks and in postnatal growth rate, supported by better development of the gastrointestinal tract (R. Kornasio et al., 2011; R. Jha et al., 2019). All amino acids are necessary for the developing embryo; the absence of any of the amino acids can disrupt protein synthesis and homeostasis in the embryo, resulting in poorer postnatal growth and development. A bulk of studies were published which demonstrated the positive effects of the in ovo injections of individual or mixed amino acids on postnatal growth rate (Y. Ohta et al., 2001; T.M. Shafey et al., 2014; L.L. Yu et al., 2018). Ca. 94 % of total metabolizable energy in the embryo is generated via the oxidation of fatty acids. These oxidative processes, in turn, generate substantial amounts of free radicals which can result in vast cellular damage (P. Surai and V.I. Fisinin, 2013; A. Yigit et al., 2014). The administration of vitamins with antioxidative activity (like С or E) during the embryonic period positively affected the postnatal development of the immune system in chicks (S.A. Selim et al., 2012; S. Nowaczewski et al., 2012). The administration of L-carnitine into the embryos was shown to enhance pre-hatch glucose utilization in the anaerobic conditions and postnatal growth in the chicks (T.M. Shafey et al., 2010; A.M. Dolgorukova, 2017). The in ovo nutrition can therefore be an instrument of significant improvement of the hatchability of the injected eggs and subsequent growth efficiency in hatched chicks, resulting in explicit economic effect (E.D. Peebles, 2018). It should, however, be noted that this technique has not still found application in the commercial poultry production and that for wider knowledge on the stimulating effects of different nutrients on the development of avian embryo further research is required.