T h e Effect of Certain Groups of Environmental Factors upon the Expression of Broodiness

BROODINESS is, to some extent, a detriment to egg production of chick-ens even with modern methods of manage-ment. The influence of environment on chickens has received considerable atten-tion, but mostly from the standpoint of egg production without particular reference to broodiness. The investigations herein reported were made at the National Agricultural Research Center, Beltsville, Maryland, as exploratory tests of the effects of some environmental factors, physical and psychological, on the expression of broodiness by chickens whose previous records had shown that they pos-sessed various degrees of broodiness. The purpose of these investigations was more to obtain an indication, if possible, of the extent to which broodiness, and inci-dentally egg production, could be influenced by psychological stimuli than to evaluate any specific stimulus or group of stimuli. The authors realize that some of the data are not as complete as could be desired, but feel that the results, such as they are, carry implications of sufficient importance to justify publication. The literature con-tains a few reports of work done in this field. Reaumur (1750) recognized the effects of certain environmental factors on the ex-pression of broodiness in chickens. He ad