Incubation temperature and post-hatch stress effects on immune parameters, immune system development, and performance in commercial broilers
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Broiler performance is dependent on immunocompetency and the ability to respond to environmental challenges. Incubation temperature, post-hatch transportation, and vaccination may impose stress upon the embryo and post-hatch chick and impact immune system development and lifetime performance of the bird. The objective of the first study was to evaluate incubation temperature and post-hatch transportation environment on response parameters indicative of early immunity in the neonatal chick. Cobb 500 eggs (n=5200) were incubated with combinations of eggshell temperatures common to commercial multi-stage incubators during early and late incubation: low (L): 36.7Â°C, standard (S): 37.5Â°C, and high (H): 39.0Â°C. After hatch, chicks were transported under one of two conditions: control (C: 34Â°C) or distressed (D: 40Â°C), yielding 8 experimental treatments: LH-C, LS-C, SH-C, SS-C, LH-D, LS-D, SH-D, and SS-D. The objective of the second study was to examine the effects of incubation temperature profiles on response to vaccination in Cobb 500 broilers (n=2000). Temperature treatments were the same as the first study, and embryos were administered vaccinations for Marekâ s disease virus (MDV) at embryonic day (ED) 18, Newcastle disease virus (NDV) at hatch, the combination of MDV+NDV, or no vaccine (control). There were 16 resulting experimental groups: LH-Control, LH-MDV, LH-NDV, LH-MDV+NDV, LS-Control, LS-MDV, LS-NDV, LS-MDV+NDV, SH-Control, SH-MDV, SH-NDV, SH-MDV+NDV, SS-Control, SS-MDV, SS-NDV, and SS-MDV+NDV. Two and three way interactions (P<0.05) were observed for the parameters evaluated and are presented for both studies. These studies suggest an influence of incubation temperature and post-hatch stressors on chick development and early immune response parameters.
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