The domestic fowl in biomedical research: physiological effects of the environment

SummaryAll animals are in a dynamic relationship with their environment. This is generally recognised by research workers and as a consequence they usually make many efforts to minimise environmental variations during their experiments. This is done in the hope of both reducing the variability of the results and safeguarding against false conclusions being drawn. The trend has, in recent times, achieved even greater importance because of the tacit assumption that more control means better data. This assumption is examined in depth in this paper.The literature on the effects of a range of environmental factors, including temperature, relative humidity, air movement, air quality, altitude, light and sound, is extensively reviewed and the implications upon experimental design considered. It is noted that the period between hatching and the start of an experiment may have a profound influence on the response observed subsequently. It follows, therefore, that information about such matters as the thermal history and the nutritional history are not just desirable but essential for good science. It does not follow, however, that there is a need for a fine control of the environment. The precision of control may well vary according to the type or nature of the experiment. Ultimately the overriding factor should be adequate control of the experiment not the environment. Translated into practical terms this means that appropriate control animals should be included in all experiments. It follows that a full description of the conditions both before and during the experiment should be included in any publication.