ENVIRONMENT, WELL-BEING, AND BEHAVIOR

ABSTRACT Effects of early life experience with cli-matic (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.-ad-ministered 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 treat-ment 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, humor-al immune competence, and endocrine responsivenes