Lighting Regimes as an Influence on Maturity and Productivity of Leghorn-Type Layers

A VOLUMINOUS literature has accumulated concerning the influence of light on the regulation of ovarian activity in birds. The subject is reviewed in depth by Biellier and Ostmann (1960). Light is not essential for sexual maturity or the continued production of eggs since birds grown and maintained in the dark commence and continue to ovulate (Rider, 1938; Wilson and Woodard, 1957; King, 1960). But regardless of this, it is clear that the length of the photoperiodic cycles exert some influence over the age when the bird begins to produce eggs and the rate and cycling of such production. Daylength was shown to have a regulatory influence on age at sexual maturity by Byerly and Knox (1946), who found that a one hour increase in sunlight at maturity was associated with a five to fifteen day reduction in the age at which the pullet matures sexually. Morris and Fox (1958a, 1960)…