Evaluation of Environmental Amenity for Animals based on Variability of Parameter of Physiological Function.

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(1) As an experimental animal model, chick embryos were investigated for their physiological functions and growth to evaluate sdverse effects of pre-incubation egg storage and failure to turn eggs during the early incubation period.(2) Two-dimensional cardiogenic ballistic trajectories were elucidated by depicting them on a computer monitor screen from ballistic signals measured simultaneously at two sites on the eggshell with laser displacement meters.(3) Another simple method to measure the cardiogenic ballistic movements (BCG) of eggs was developed by taking advantage of an electromagnetic induction coil (solenoid) and small permanent magnet as a sensor. Numerical model analysis was made to design a measuring system and the BCG was successfully measured from late chick embryos.(4) A noninvasive system of instantaneous heart rate (IHR) was developed using acoustocardiogram and determined the IHR and its variability of individual chick embryos during the last half of incubation. Characteristic, transient bradycardia was found to occur on days 14-15 and the embryonic cardiac rhythm became more arrhythmic with further development. Experiments using intravenous administration technique of autonomic drugs showed no relationship between functional development of autonomic nerves and unique embryonic arrhythmia and heart rate variability (HRV). These new evidences prompt us further study to elucidate the HRV.(5) It was hypothesized that the optimal incubation temperature (38ﾟC) in air provides developing embryos with the most favorable amenity and the HRV is at maximum in the favorable amenity. The IHR and HRV of developing embryos were determined at 38ﾟC in air and during acute exposure to altered environments (low or high temperature, and hypoxic or hyperoxic environment). Preliminary results indicate that the HRV decreases in an altered environment and detailed experiments are in progress.