The Influence of Early Photoperiod Lengths on Birds Maintained Under “Short Days”

Numerous reports have been published regarding the influence of different lighting programs on sexual maturity and subsequent egg production in the domestic fowl (King, 1961; Morris and Fox, 1960; Bowman and Jones, 1961). Little information is available, however, on the effect of photoperiod length prior to maturity on birds subjected to day lengths shorter than 24 hours (“short days”). Davis et al. (1964) subjected birds maintained under “short days” to different light regimes from 12 to 18 weeks of age and noted that birds receiving a 12-hour dark period per cycle matured earlier than other treatment groups. This report involves the response of birds maintained under 18-hour “short days” to both constant and decreasing photoperiod lengths during the growing period. METHODS Approximately 300 Cornell Randombred female chicks were divided equally among four pens of a controlled environment windowless house in both 1962 and 1963. Birds in two pens received a . . .