Effects of in ovo feeding on turkey embryos development, energy status, intestinal maturation, gene expression and post-hatch development

Glycogen stored in liver and muscles are the main energy source during hatching of poultry. Turkey embryos are very sensitive to perturbations in energy metabolism because they have a wider hatching window than chicken embryos. Mortality of turkey embryos during late-term incubation is high relative to chickens, and many surviving hatchlings have compromised vitality. In ovo feeding (IOF) improves the energy status and gut development of perinatal poultry by supplementing the amnion with nutrients, which is then orally consumed by the embryo prior to hatch. A survey of amnion and embryonic development was done to determine the best time, maximum volume and solution characteristics for IOF. Several IOF formulations containing combinations of carbohydrates, proteins and enteric modulators were tested in turkey eggs, with emphasis on comparing hydrolyzed soy protein to egg white. IOF was found to improve energy status at hatch, but subsequent growth performance results were inconsistent. Therefore, further studies were designed to better understand late-term turkey embryo metabolism, using a customized focused oligonucleotide microarray. A gene expression survey using this array was performed on liver, pectoral muscle, hatching muscle, duodenum, and ileum of turkey embryos from 20 days of incubation until hatch. The embryos were found to switch from yolk fat to carbohydrate-based metabolism around 22 days of incubation, and potential substrates were identified to be tested in ovo. A nutritive solution containing metabolic co-factors was then formulated and tested in a subsequent IOF experiment. At hatch, poults treated with this latest IOF formulation exhibited better quality scores and more symmetric legs than controls. Gene expression patterns of liver, pectoral muscle, hatching muscle, duodenum and ileum confirmed IOF favored skeletal development of poults. This dissertation research clearly demonstrated that in ovo feeding technology can enhance energy status and advance the development of hatchlings, resulting in superior poult quality.