Comparison of a modern broiler and layer strain during embryonic development and the hatching process

• Published in: British poultry science Vol. 49; no. 5; pp. 574 - 582
• Main Authors: Everaert, N, Willemsen, H, Smit, L. De, Witters, A, Baerdemaeker, J. De, Decuypere, E, Bruggeman, V
• Format: Journal Article Web Resource
• Language: English
• Published: England Taylor & Francis Group 01.09.2008; Taylor & Francis
• Subjects: Aging; animal growth; Animal production & animal husbandry; Animals; blood chemistry; blood gases; body weight; broiler chickens; Carbon Dioxide; Chick Embryo - growth & development; Chickens - genetics; Chickens - growth & development; Chickens/genetics/growth & development; chicks; corticosterone; Corticosterone - blood; egg shell formation; egg weight; egg yolk; Egg Yolk - physiology; embryo (animal); embryogenesis; hatching; hormone secretion; laying hens; Life sciences; ova; Ovum - physiology; Oxygen; Partial Pressure; Productions animales & zootechnie; Sciences du vivant; strain differences; strains; temporal variation; thyroid hormones; Thyroxine - blood; Triiodothyronine - blood
• ISSN: 0007-1668; 1466-1799; 1466-1799
• DOI: 10.1080/00071660802357025

1. This research focused on the embryonic development of broiler and layer embryos. 2. Egg, embryo and yolk weights were measured and partial pressure of gases in the air cell and blood were analysed at several embryonic ages. The static stiffness of the eggshell was measured before the start of incubation and at embryonic day (ED) 18 to register the change in shell strength. Times of internal pipping (IP), external pipping (EP) and hatch were recorded. Plasma corticosterone, triiodothyronine and thyroxine concentrations were determined. 3. Relative egg weight loss was higher in layer eggs. Before ED16, layer embryos showed a slower development which was reflected in lower (relative) embryo weight, lower air cell and blood pCO2 and higher air cell O2. From ED16 onwards, relative growth rate accelerated in the layer strain; as a consequence the difference in relative yolk-free chick weight at hatch had disappeared between strains. 4. Differences in physiological events necessary for hatching (thyroid hormones, corticosterone, air cell pCO2) are most probably responsible for the observed differences in timing of pipping and hatching events between layer and broilers.