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ENVIRONMENT, WELL-BEING, AND BEHAVIOR |

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* Adaptation Physiology Group, Wageningen Institute of Animal Sciences, Wageningen University, PO Box 338, 6700 AH Wageningen, the Netherlands;
Department of Animal Health, Welfare and Nutrition, Faculty of Agricultural Sciences, University of Aarhus, PO Box 50, DK-8830 Tjele, Denmark; and
Laboratory of Livestock Physiology and Immunology, Department of Biosystems, Catholic University Leuven, Kasteelpark Arenberg 30, 3001 Leuven, Belgium
1 Corresponding author: henk.parmentier{at}wur.nl
Effects of early life experience with climatic (heat) and hygienic [lipopolysaccharide (LPS)] stress on adaptability to the same stressors in later life were studied in laying hens. Chicks were exposed to 37°C for 24 h at d 5 of age (n = 12) or were i.v.-administered once with 1 mg/kg of BW of LPS at 6 wk of age (n = 12), whereas a control group was reared under standard conditions receiving a placebo treatment of PBS (n = 36). At 24 wk of age, hens treated in early life were reexposed to the same stressor. Early life control hens were exposed to heat stress (n = 12), i.v.-administered with LPS (n = 12), or not exposed (n = 12). To evaluate improvement of adaptability, effects of climatic and hygienic stress on performance, humoral immune competence, and endocrine responsiveness were investigated in hens with early life experience to the stressors and hens only exposed to the stressors in later life. Early life heat exposure did not affect performance, immune, and endocrine parameters. Treatment x time interactions were found for level of antibody (Ab) binding to LPS and keyhole limpet hemocyanin (KLH) after LPS administration, indicating that hens with early life LPS experience differed in response level (Ab binding to LPS) and response pattern (Ab binding to LPS and KLH) compared with hens administered with LPS only at adult age. Our data suggest that early life heat stress exposure did not affect adaptability of laying hens to heat stress in later life. However, early life LPS exposure affected kinetics and magnitude of Ab levels binding to LPS and KLH, indicating that early life LPS exposure can enhance the status of immune reactivity or induce a higher sensitivity to LPS.
Key Words: early life experience heat stress antibody lipopolysaccharide performance
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