Effect of Lighting Systems in the Grower and Adult Periods Upon the Over-All Performance of White Leghorns

The Effect of Photoperiodism and Rearing Period Feed Restriction on the Performance of Five Leghorn Strains

“…This suggests that a rearing period day-length of less than 9 hours, at a critical time in the rearing period, may result in a reduction in subsequent egg size. These results agree with reports by Siegel et al (1963), Bowman et al (1964), Berg et al (1963) and Lillie and Denton (1965) who reported that day-length declining to 6 to 8 hours or maintained on a constant 6-to 8-hour length resulted in a mean egg size reduction compared with a longer day-length.…”

“…These results are contrary to reports by McClary (1964), and Morris et al (1964) which suggest that a "step-down, step-up" light treatment is superior to other treatments, but Berg et al (1963) and Lillie and Denton (1965) reported that a constant 14-to 16-hour day-length resulted in equivalent egg production compared with other light treatments which supports results reported here. Smith and Noles (1963), Lowe and Heywang (1964), and Noles and Smith (1964) worked with a wide variety of light treatments which included a 14-to 16-hour laying period day-length but failed to demonstrate a marked advantage for one treat-ment over another.…”

“…The experimental procedures used by different workers in the study of photoperiodism have varied widely and results tend to be somewhat contradictory. Biellier and Ostmann (1960), and more recently, Smith and Noles (1963), Davis et al (1964) and Lillie and Denton (1965) have reviewed the literature on the effects of different photoperiods on the performance of egg production stock. A number of reports indicate that performance was improved for some traits when an increasing laying period day-length is coupled with either a constant 6-to 8-hour rearing period day-length or a rearing period with a day-length which is shortened, by equal weekly decrements, from day-old to housing age.…”

“…Smith and Noles (1963) reported that the performance of laying stock on a constant 15-hour laying period day-length was equal or superior to the performance of birds under light treatments. Lillie and Denton (1965) working with March-hatched chicks reported that, "different lighting systems had no advantage over the conventional lighting program (natural day-length, or 14 hours constant light in grower period plus 14 hours constant light in adult period) for all traits studied." Strain X light treatment interactions have not been studied extensively.…”

Studies with Decreasing Lighting Regimes for Early-Season Replacement Pullets under Subtropical Conditions

“…Already after the first week the increased consumption in the lighted pens amounted to as much as 10%, and at times almost one-third of the total feed intake was consumed during the period of artificial illumination. This phenomenon has been described for DLR by Morris and Fox (I960), Noles and Smith (1964) and Lillie and Denton (1965), and for various schedules of constant lighting by King (1961). It can be assumed that this effect is due to light supplementation per se, rather than being the specific result of DLR.…”