The Influence of Different Light Day Distribution in Hy-Line W36 Laying Hens on Egg Production and Egg Quality.

Laying hens are commonly provided with 16 h of continuous light and 8 h of continuous darkness, with eggshell calcification largely developing during dark hours when dietary calcium is depleted simultaneously with the daily fasting period in laying hens. This phenomenon is thought to be the leading cause of osteoporosis in modern commercial flocks. This trial examined how disrupting the midnight phase affected egg quality in Hy-line W36 hens assigned to control (C) or treatment groups (W1 or W2) from 20 to 70 weeks of age. C hens received 16 h of light and 8 h of dark. W1 hens received 1 h of scotophase interruption, whereas W2 hens received 2 h of scotophase interruption. Across weeks, performance, production, and egg quality measures were measured ( < 0.05). Scotophase interruption displayed a positive effect on the treatment groups in terms of HDEP (week 50: = 0.028, 0.016; week 70 = 0.031,0.022), damaged eggs (week 50: = 0.012, 0.021, week 70: = 0.019, 0.025), eggshell weight (week 30: = 0.021, 0.027; week 50: = 0.022, 0.024; week 70; = 0.018, 0.019), eggshell thickness (week 30: = 0.017, 0.022; week 50: = 0.018, 0.031; week 70; = 0.029, 0.033), ash percent week 30: = 0.027, 0.021; week 50: = 0.012, 0.014; week 70; = 0.031, 0.034), and eggshell strength (week 30: = 0.025, 0.023; week 50: = 0.019, 0.021; week 70; = 0.029, 0.015) in W1 and W2 birds compared to C birds.