Physiological responses to heat stress in two genetically distinct chicken inbred lines

Abstract

High ambient temperature is one of the most important environmental factors negatively impacting poultry production and health. Genetics is an important contributor in mitigating the stress response to heat. Two genetically distinct highly inbred lines of similar body size (Leghorn and Fayoumi) were characterized for phenotypic differences in response to heat. At 14 days of age, birds were exposed to 38°C with 50% humidity for 4 hours, then 35°C until the conclusion of the experiment. Non-treated individuals were kept at 29.4°C for the first week and then 25°C throughout the experiment. Birds in the heat-stress group were inoculated at day (d) 21 with Newcastle disease virus (NDV) La Sota strain to investigate the effects of heat stress and NDV infection. Thirteen blood parameters were measured using the iSTAT blood analyzer at three stages: 4 h, 6 d, and 9 d post heat-stress treatment, representing acute heat (AH) exposure, chronic heat (CH1) exposure, and chronic heat exposure after virus infection (CH2), respectively. Most blood parameters were significantly changed with heat stress in Leghorns at AH and in Fayoumis at CH1 and CH2. The Leghorn line had significant acute responses with disrupted acid-base balance and metabolic disorders. The heat-resilient Fayoumis maintained a relatively well-balanced acid-base balance. The current study provides the comprehensive profile of biomarker signatures in blood associated with heat tolerance and suggests that PO2, TCO2, HCO3, and base excess can be served as potential biomarkers that can be used to genetically improve heat tolerance in poultry.

Integrated Transcriptome and Histone Modification Analysis Reveals NDV Infection Under Heat Stress Affects Bursa Development and Proliferation in Susceptible Chicken Line

“…The two inbred chicken lines used in this study are Fayoumi (M15.2) and Leghorn (GHs 6), which are maintained at ISU (Ames, IA, United States). The experimental design has been described in previous publications ( Saelao et al, 2018a , b ; Wang et al, 2018 ). Upon arriving from ISU, chicks were randomly divided into a non-treated and treated group for each line.…”

“…Additionally, Fayoumi is hypothesized to be more heat stress-resistant because the line originated from Egypt therefore historically had adapted through natural selection to an environment with higher climate (Wang et al, 2014;Deist et al, 2017;Saelao et al, 2018b). Physiological responses to heat stress have been shown to be significantly different between the two lines, with electrolyte levels appearing to be more well-maintained during heat stress in Fayoumis compared to Leghorns (Wang et al, 2018).…”

Liver Transcriptome Responses to Heat Stress and Newcastle Disease Virus Infection in Genetically Distinct Chicken Inbred Lines

“…Characterization of genetically controlled physiological parameters that vary in response to heat stress will lay the foundation for utilizing these parameters as potential markers to select for heat stress resilience [ 13 ]. In our recent study, physiological parameters from two genetically distinct, highly inbred lines (Leghorn and Fayoumi) were measured and analyzed [ 14 ]. These two genetic lines responded differently during heat stress, especially at the acute heat stage.…”

Effect of broiler genetics, age, and gender on performance and blood chemistry

“…(2005) using hematological profiling. While other studies have focused on hematological and biochemical reference ranges only with regard to a specific time, strain, region, or sex ( Adeleye et al., 2018 ; Al-Nedawi, 2018 ; Nanbol et al., 2016 ), others have studied the effects of various treatments on hematology including feeding allopurinol to reduce uric acid levels ( Klandorf et al., 2001 ) or the effect of heat stress on similar blood biomarkers ( Wang et al., 2018 ). Regardless of the objective, these hematological profiling experiments have occurred with increasing frequency.…”