Hypercapnic thresholds for embryonic acid–base metabolic compensation and hematological regulation during CO2 challenges in layer and broiler chicken strains

Abstract

Time specific acid-base metabolic compensation and responses of hematological respiratory variables were measured in day 15 layer (Hyline) and broiler (Cornish Rock) chicken embryos during acute hypercapnic challenges (3, 6, 10 and 20% CO2). Control acid-base status and hematology differed between two strains. Broiler embryos were relatively respiratory acidotic and had higher hematocrit (Hct) and hemoglobin concentration. The partial metabolic compensation for respiratory acidosis produced by ≤ 10% CO2 exposures occurred in proportion to CO2 concentrations in both strains, but metabolic compensation for 20% CO2 respiratory acidosis was depressed at 2, 6 and 24h, particularly in broiler embryos. Exposure to ≤ 10% CO2 induced the same hematological responses across CO2 concentrations; i.e., Hct and mean corpuscular volume (MCV) increased while RBC concentration remained unchanged. In response to 20% CO2 exposure, Hct and MCV increased dramatically in both stains. Consequently, altered acid-base and hematology responses to 20% CO2 exposure compared to ≤ 10% CO2 suggest that the hypercapnic threshold to compensation for acidosis and regulation of hematology is >10% CO2.

Cardio-respiratory development in bird embryos: new insights from a venerable animal model

“…These approaches are often combined with exposure of the developing embryo to hypoxia or hypercapnia as stressors on the cardiovascular, respiratory, and acidbase balance systems to tease apart elements of cardiorespiratory physiological control (Adair et al, 1987;Strick et al, 1991;Burton and Palmer, 1992;Rouwet et al, 2002;Crossley et al, 2003a;Villamor et al, 2004;Fisher and Burggren, 2007;Copeland and Dzialowski, 2009;Lindgren and Altimiras, 2009;Acosta and Hernandez, 2012;Zhang and Burggren, 2012;Mueller et al, 2013b;Andrewartha et al, 2014;Mueller et al, 2014b;Burggren et al, 2015b;Jonker et al, 2015;Itani et al, 2016). …”

“…What might be the source of this variation in the morphological and physiological responses, and even the apparent timing of the critical windows, of avian embryos in response to hypoxic incubation? Certainly, there are specific physiologies and morphologies attached to specific strains of chickens, with often profound differences in magnitude and developmental timing of the response (Sato et al, 2006;Everaert et al, 2008b;Druyan, 2010;Ho et al, 2011;Crossley and Altimiras, 2012;Burggren et al, 2015b;Buzala et al, 2015;Huth and Archer, 2015). All too often, the specifics of the strain of chicken are not provided in studies, leaving open the fact that strain-specific differences are contributing to the apparent variability between published studies.…”

“…Hypercapnia has been widely used as a stressor to probe the onset of acid-base balance; discussion of this extensive literature is beyond the scope of this review, and the reader is referred to the following studies for an entry into the literature Everaert et al, 2008a;Everaert et al, 2011;Tazawa et al, 2012;Burggren et al, 2012;Mueller et al, 2013b;Andrewartha et al, 2014;Mueller et al, 2014b;Burggren et al, 2015b;Mueller et al, 2015a). Like hypoxia, hypercapnia has differential levels in mortality/hatchability at different points in development (Taylor and Kreutziger, 1966;Taylor and Kreutziger, 1969;Everaert et al, 2007).…”

Data mining as a hatchery process evaluation tool

“…Classic data processing methods are at times not efficient in elaborating biological responses and factors (Mehri, 2013) such as genetic selection for meat or egg production, which influence the development and metabolism of the embryo during the hatching process (Buzala et al, 2015;Burggren et al, 2015).…”