The Effects of Ahemeral Light-Dark Cycles Early in the Laying Cycle on Egg Production in White Leghorn Hens

Abstract

Studies were conducted to compare the effects of two ahemeral (AH) light-dark cycles of 26 and 28 h (AH26 and AH28) with a 24-h hemeral (H) cycle early in the lay cycle on egg production and size. Nine rooms, three per treatment, each holding 264 hens, were maintained with identical photoperiods. The scotoperiod was increased to provide (he desired AH “day length” at 20 wk of age. Later decreases of the AH cycles back to the H cycle were accomplished by decreasing the scotoperiod only.There were no significant differences in egg production in Experiment 1 for both AH26 and AH28 compared with the H control. However, egg size as percentage of large (56 g) and above was significantly improved at 28 wk of age for both AH treatments.In Experiment 2, egg size was again significantly higher for AH28. This was accompanied by a significant increase in egg production for 28-day Periods 1 and 2 and a decrease in Periods 3, 7, and 10 versus H.A new AH26 lighting program was then tested in Experiments 3 and 4. This resulted in significant increases in egg production for Periods 2 (Experiment 3) and 1 (Experiment 4). Within experiment, annual egg production was similar for H and AH26 birds. Egg size, as percentage of large and above, was also significantly increased for AH26 at 25, 26, 27, and 29 wk of age (Experiment 3) and 26 wk (Experiment 4).A tested AH26 lighting program leading to increased pullet egg size with no loss in egg numbers for 20-wk-old pullets is outlined.