Biological factors affecting poultry embryo quality

• Author / Creator

  Hamidu, Jacob Alhassan

• The objectives of this thesis were to investigate some physiological, cellular and molecular changes from genetic selection, flock age and egg storage on embryonic metabolism, cell viability and gene expression in poultry species. Embryonic heat production (EHP), the parameter used to evaluate metabolic status of two turkey genetic strains (Nicholas and Hybrid) and four flock ages (30 wk, 34 wk, 55 wk, 60 wk) were determined. The results showed that embryos of older flocks had higher EHP than all other flock ages. The higher metabolism can cause overheating in embryos from older flocks during the later part of incubation. The EHP values can assist incubator manufacturers and hatchery managers to manage incubation temperatures to increase embryo survival. The EHP was also determined in two Ross 308 broiler breeder egg storage durations (4 d and 14 d) to assess the impact of long-term egg storage on embryonic metabolism. The embryos from 4 d stored eggs had higher body weight and EHP than embryos from 14 d stored eggs. To investigate what could be the fundamental reasons for the metabolic differences, blastoderms from eggs in these egg storage treatments were isolated, dissociated into single cells, stained with fluorescent dyes and subjected to flow cytometry analysis to differentiate between viable (live), apoptotic and necrotic cell populations. Quantitative real time PCR analysis was then used to compare the expression of selected apoptotic genes (Bak, Bax, Bok, Bcl-2, Bcl-xL) in blastoderms and embryos from 6 d incubated eggs. While percentage of viable cells decreased significantly, an unregulated amount of apoptosis increased with egg storage duration (p < 0.0001). Expression of pro-apoptotic genes (Bak, Bax, and Bok) were up regulated as storage duration increased at the blastodermal level but all genes were down regulated after 6 d of incubation. This suggests that an increment in egg storage duration can cause activation of apoptotic cell death mechanisms at the blastodermal level, which can be one of the molecular mechanisms that led to the reduced daily embryonic growth and metabolism observed in 14 d stored eggs. The thesis suggests there are molecular and cellular implications of egg storage.

• Subjects / Keywords

  • Genetic strain
  • flock age
  • egg storage
  • embryo quality

• Graduation date

  Spring 2011

• Type of Item

  Thesis

• Degree

  Doctor of Philosophy

• DOI

  https://doi.org/10.7939/R39C9V

• License

  This thesis is made available by the University of Alberta Libraries with permission of the copyright owner solely for non-commercial purposes. This thesis, or any portion thereof, may not otherwise be copied or reproduced without the written consent of the copyright owner, except to the extent permitted by Canadian copyright law.