Age-related effect of high-frequency LED lighting in laying hens on biochemical, enzymatical, and electrolytes variables

SUMMARY: A novel lighting system using high-frequency differential photostimulation developed for layer chickens was assessed for its effects on physiological response. In each of the 2 trials, a total of 320 ten-wk-old layer pullets were randomly allocated to 16 groups with 20 birds/group. Birds were weighed and randomly assigned to each of 4 cage banks in each of 4 rooms. Experimental treatments included the prototype LED lighting system and conventional 2700K LED bulbs. Photoperiod for the prototype system was 24L:0D per the manufacturer's recommendations and photoperiod for the conventional system followed the Hy-Line Management Guide. Blood samples (3 mL) were collected from the brachial wing vein into heparinized syringes within 45 s after birds were caught from 8 randomly selected birds per room for a total of 32 birds at each blood sampling day of placement, prior to point of lay, and at the termination of the study for a total of 96 birds. Plasma was separated from blood samples by centrifugation and used to determine the concentration of biochemical parameters and enzyme activities using an ACE-AXCEL automatic analyzer. Also, estradiol, follicle stimulating hormone, corticosterone, melatonin, T3, and T4 levels using Tosoh A1A-360 automatic analyzer. Results show that only uric acid (UA) and estradiol were affected by treatments. However, woa had significant effects on most examined variables. Plasma corticosterone was not affected by treatments and woa, indicating absence of physiological stress. In conclusion, using high-frequency LED lighting in layer hen houses does not negatively affect layer hens’ welfare