Abstract
Transportation is a stressful procedure that can alter end-of-cycle hen (EOCH) behavior and physiology. This study (5 × 3 × 2 factorial arrangement) aimed to assess the effects of temperature (T)/relative humidity (RH) (-10°C uncontrolled RH (-10), +21°C 30%RH (21/30), +21°C 80%RH (21/80), +30°C 30%RH (30/30), +30°C 80%RH (30/80)), duration (4, 8, 12 h), and feather cover [well (WF) and poorly-feathered (PF)] on white-feathered EOCH (65-70 wk) behavior and physiology. EOCH (n = 630) from 3 commercial farms were housed for adaptation (3-5 d), fasted (6 h), crated (53 kg/m(2)), and placed in a climate-controlled chamber. Data collected included chamber and crate conditions, feather condition score, mortality, core body temperature (CBT), behavior, and delta (∆) blood physiology. Analyses were conducted via ANOVA in a randomized complete block design (farm of origin) with significance declared at P ≤ 0.05. PF EOCH had higher mortality than WF hens during cold exposure (-10). EOCH ∆CBT demonstrated a greater (positive) change at 12 h for all T/RH compared to 4 h at 21/30, 21/80, and -10 (negative). Cold exposure (-10) resulted in a higher percentage of time spent shivering and motionless, while heat exposure resulted in a higher percentage of time spent panting for WF EOCH exposed to 30/30 and WF and PF hens exposed to 30/80. Hen ∆glucose had a greater (negative) change at 4 and 12 h for -10 compared to 4 h at 21/30, and all durations for 21/80, 30/30, and 30/80. PF hens exposed to -10 had a greater (positive) change in ∆sodium, ∆hemoglobin, and ∆hematocrit compared to WF birds (negative). The development of metabolic alkalosis was supported by the increase in ∆blood pH over time and the increase in ∆partial pressure of carbon dioxide, ∆bicarbonate, and ∆base excess extracellular fluid during cold exposure (-10). These results indicated that EOCH exposed to heat endured thermal stress while PF hens exposed to cold were unable to cope with cold stress.