Do flickering LED lights reduce productivity of layer pullets and hens?

Most characteristics of artificial light sources are well studied, however light-flicker frequency (F) has been overlooked. The purpose of this study was to determine the effect of F on performance of Lohmann LSL-Lite (LW) pullets and Lohmann Brown-Lite (LB) pullets. In addition, pullets were followed through to the laying phase to evaluate long-term effects of F during rearing on productivity. Two trials were conducted with 3 F (30, 90, or 250 Hz) treatments. LW and LB pullets (n = 2,688 per strain [S]) were randomly assigned to floor pens within 8 light-tight rooms (15 pen replicates per F × S for 30 and 250 Hz; 18 pen replicates per F × S for 90 Hz). At 16 wk, pullets were transferred to conventional layer cages, with no flicker treatment applied. Pullet data collected included BW, feed disappearance, flock uniformity, and overall mortality. Hen data collected included BW, feed intake (feed efficiency calculated), mortality, egg production, and egg quality. Data were analyzed using Proc Mixed (SAS 9.4) and differences were considered significant when P ≤ 0.05. Frequency did not affect pullet uniformity or feed disappearance (0-8 wk and 0-16 wk). Pullets reared under 30 Hz had higher mortality (caused by "other") than those reared under 250 Hz. Lohmann Brown-Lite pullets reared under 30 Hz had the highest feed disappearance. Overall mortality was higher for LW pullets reared under 30 Hz compared to LB reared under 30 Hz or 250 Hz. Lohmann Brown-Lite hens reared under 30 Hz were heavier at the beginning of the hen phase (17 wk), however differences related to F were not seen at 40 or 48 wk. Hen day production (%) was higher for hens reared under 30 compared to 90 Hz (P = 0.03), however no other egg parameters were affected by F. Hen feed efficiency and mortality were unaffected by F. These results indicate minor effects of F, during either the pullet or hen phases. The data also suggest that S (LW vs. LB) may affect response to F.