Prelay light restriction of turkey hens: daylength versus exposure time

A 3 x 3 factorial experimental design was used to examine the relationship between the duration of short daylength (10, 8, or 4 h light/day) during prelay light restriction and the length of time (12, 8, or 6 wk) that young turkey hens were exposed to light restriction and subsequent photoinduced reproductive performance. Data were collected for time to first egg, egg production, percentage of fertility, and hatchability, and poult weight. Light restrictions consisting of 10, 8, or 4 h light/day were equally effective in terminating photorefractoriness and preparing hens for subsequent photoinduced reproductive performance. A 6-wk exposure to light restriction did not prepare hens for egg laying as effectively as 8 (P less than .05) or 12 (P less than .10) wk of exposure, both of which were similarly effective. A lack of interaction between the light restriction daylength and exposure time suggests that the requirements for effective light restriction are rather specific and cannot be beneficially manipulated by various combinations of daylength and weeks of exposure.